lens of 5 or 6 inches focus; if one of longer focus be used, the dispersion of light becomes too great to ensure an accurate representation. When the tree or shrub is well illuminated by the solar beams, the lens should be presented towards it, at a distance varying of course with the height of the object. A piece of card-board should then be placed in the box, a little beyond the true focus of the lens, and the former moved until a well-defined bright image of the tree &c. is formed on the card, of course in an inverted direction. The box is then to be placed on any convenient support in this position, and a piece of the prepared paper fixed on the card, the lid of the box is then to be closed, and the whole left for half an hour, at the end of which time a beautifully accurate outline of the object will be found on the paper, which is then to be rendered permanent in the usual manner. It is obvious that this plan is unavailable on a windy day, on account of the branches of the tree &c. being continually moving, so that it is of far less use to the botanist than the above described process for obtaining drawings of small specimens. Various other applications of this paper will suggest themselves to the minds of naturalists, but having far exceeded my intended limits, I conclude by subscribing myself, 22, Wilmington Square, March 25th, 1839. Yours very faithfully, THE MAGAZINE OF NATURAL HISTORY. APRIL, 1839. THE Memoir of Madame Power upon the Paper Nautilus and the cephalopodous animal as yet its only known occupant, originally published in the Proceedings of the Academy of Catania, is concluded in our present number: and to those who feel at all curious upon the subject, the history of this lady's researches will furnish matter of extreme interest. To us it appears that the observations of Madame Power, in connection with evidence subsequently drawn from materials in her possession, all but demonstrate the relation between the poulp and the argonaut-shell, to be one of necessity and not of convenience. At all events, this long-disputed question will henceforward hold a position very different to that which it has for a long period occupied; for it will hardly now be assert ed that the arguments for and against the parasitic hypothesis are equally balanced. We admit that in some particulars Madame Power's descriptive details are open to objection, as being sometimes evidently inaccurate; but this, to a great extent, may be explained as a consequence resulting from her want of physiological knowledge, and partly from a very natural wish on her part not to appear ignorant of things which she supposed every body knew. Fortunately it happens that some of the more important facts bearing upon the question at issue, although originating in the researches of this lady, do not rest upon her individual testimony as the sole authority for their existence. M. Sander Rang has fully confirmed all that she has stated of the manner in which the poulp applies its palmated or sail-arms to the keel and sides of the shell; and Professor Owen, at a recent meeting of the Zoological Society, communicated the result of his own observations upon the materials placed at his disposal by Madame Power. In a series of ova exhibiting various stages of developement, he found in those most advanced the contained embryo having the distinction of body and head established; the pigment of the eyes, the ink in the ink-bladder, the pigmental spots on the skin were distinctly apparent; the siphon, the beak, and the arms were also discriminated by a low microscopic power; but no trace of the shell. Now Madame Power has uniformly asserted that the young poulp is excluded naked from the egg, although fully cognisant of Poli's belief that he had detected the embryo-shell within the ovum; and the result of Prof. Owen's examination is therefore strong presumptive evidence in favor of her statement. With respect to the supposed exception among the testaceous Mollusca which the young of the poulp would form, (granting the condition of its naked exclusion from the egg), and the consequent inference which might be drawn in favor of the parasitic theory, Mr. Owen observed that the mode of the development of the ova of Mollusca has not been investigated even to the amount of one per cent., so that the data are far too imperfect for arriving at even a general law respecting the existence of the shell within the ovum, and much less one so precise as almost to prohibit the possibility of a cephalopod that is born naked secreting a shell some days afterwards. The collection of argonauts with the respective animals brought by Madame Power on her present visit to this country, consists of twenty specimens in all stages of growth. In every case Mr. Owen found that the position of the cephalopod with respect to the shell corresponded to that in the pearly nautilus; in the young specimens the body of the cephalopod was exactly adapted to the whole cavity of the shell, but was withdrawn from the apex in those of a larger size, and the deserted place filled with the mucous secretion or ova of the animal. The argonaut-shells which had been perforated or fractured by Madame Power, and subsequently repaired whilst in her possession, went very far towards convincing us that the two kinds of repairing material which we have described on a former occasion1 are deposited by one and the same mollusc, being merely different stages of a continued secretive process. Perhaps, however, the most convincing argument put forward by Mr. Owen, is this. The young cephalopod grows rapidly, and a uniform correspondence is found between its size and that of the shell which it inhabits; consequently, upon the parasitic hypothesis, the young Ocythoë must be engaged in waging continual warfare with the hypothetical true constructors of the argonaut shell, and the number of these hypothetical true constructors must infinitely exceed the number of the hypothetical parasitic occupiers; now from the abundance in which Madame Power has procured cephalopods and shells, the hypothetical true constructors ought to swarm in the port of Messina, and yet this great desideratum in the science of Malacology has not only evaded her observation, but the observation of all other collectors who have explored the coasts of the Mediterranean. The entire summary of Mr. Murchison's researches upon the group of ancient fossiliferous rocks, to which he has applied the term "Silurian System," has appeared in two quarto volumes, accompanied by a splendid suite of maps and illustrations. Altogether we think this work must be regarded as the most important memoir, of a purely geological character, that has ever appeared in this, or perhaps any other country. Nothing but the high reputation with which Mr. Murchison's name must always be associated wherever Geology is known as a science, in connection with the "Silurian System," can in any way recompense him for the labour it must have cost in its production. We make this casual allusion to the appearance of the work, reserving for another occasion a more extended notice of its contents. The Report by Mr. De la Beche on the Geology of Devon, and critical notices of many other geological works acknowledged on our wrapper, and with which our library table is almost covered, are, from the pressure of original articles, postponed for the present. A work has been published within the last few days, entitled 'Proceedings of the Botanical Society of London, from July, 1836, to November, 1838.' We imagine that the majority of metropolitan botanists would feel somewhat indignant if the condition of botanical science in the capital of Britain were to be, in any way, tested by the contents of this vo 'Mag. Nat. Hist.' n. s. vol. i. page 528. lume. The anxiety of the Council to see their own names, or the name of the Society, in print, has overreached their discretion, or they certainly would have avoided a public record of their proceedings, so long as the reading of articles from foreign journals, in lieu of original papers, occupied the business of their monthly meetings. Belonging to the Society in question, we feel at liberty thus to express our sentiments, because we think the volume, taken as a whole, is not creditable to the Society, and calculated rather to keep it in the rear, instead of contributing to place it on a level with other bodies of a kindred nature. The plant allied to Nymphea, and transmitted to this country from Guana by Schomburgh, is figured and described under the name Victoria Regina, Schomburgh, though in the 'Magazine of Zoology and Botany,' vol ii. page 440, it is published as Victoria Regina, Gray. The Society, it appears, has adopted this plant as its emblem, the Queen having, in accordance with the wish of its discoverer, granted permission for the use of her name to designate the genus. Should Her Most Gracious Majesty Queen Victoria have the curiosity to look at the description of this Royal plant, what must be her astonishment, if the elements of Botany and the rudiments of Latin have formed a part of Her Majesty's education, to find that under the sanction of the Botanical Society of London, or at any rate that of the Council, this said Royal plant, Victoria Regina, is characterised as having "foliis orbiculatis, supra reticulato areolatis utrinque glabro; nervis venisque subtus prominentis aculeatis.” Messrs. Doubleday and Foster have been welcomed on their return from America, with a dinner by their entomological friends, principally intended as a public acknowledgment for the time and expense devoted by these two gentlemen to the advancement of science, and the liberal manner in which they intend to dispose of the rich collection formed during their travels. On this occasion the uniform cordiality and kindness they had experienced among American naturalists, was spoken of in the warmest terms of grateful recollection. It will be seen by a notice on the second page of the wrapper, that with the May number of this Magazine a supplementary part, containing plates will be issued. The introduction of Memoirs illustrated by plates constitutes a new feature in the publication of this journal, and one to which we respectfully invite the attention and support of our subscribers. We have long considered the limiting the illustrations to wood-cuts a 1 It is understood that the collection will be distributed among the public cabinets of the metropolis. drawback to the Magazine, not only from its excluding certain papers which would otherwise gain insertion, but by its preventing the work from taking that rank in scientific literature to which the number and character of its contributors fairly entitle it. We have thought it better to publish the plates in a separate form, rather than to make an alteration in the price of the Magazine, intending the purchase of the supplement, (after the issue of the first number), to be quite optional with the subscribers. It is proposed to publish about three of these supplementary parts in the course of a twelvemonth, and not in any way to reduce the number of woodcuts in the body of the Magazine. SHORT COMMUNICATIONS. LIMNORIA terebrans in Plymouth Harbour.-In my paper onthe Teredo and Limnoria (vol. ii. n. s. page 206) I stated that I had submitted Kyanized wood to the test of the action of the Limnoria; accordingly on the 12th of January, 1838, I placed the following pieces of wood on the piles of the PitchHouse Jetty, in Plymouth Dock-Yard, at low water; a piece of American deal, 4 inches by 10 thick; also a piece of similar dimensions, which had been soaked for two months in a saturated solution of arsenic; and two others which had been prepared with Kyan's solution, by W. Evans, Esq., the agent of the patentee in this town. On the 12th of the following August, the pieces having all been under water for seven months, were taken up by some of the dock-yard men in presence of Mr. Churchward and myself, and they are now in my possession. It was found that the protected pieces had all been acted on, though not to quite so great an extent as the plain piece of deal; but the specimens were dotted with Balani and Flustre, and all contained living Limnoriæ, and it was evident that, though retarded, the destruction of the wood would, in a few months more, have been equally as certain as where none of the above preparations had been employed. It appears to me highly improbable that any protection can be afforded in cases of this kind, from the employment of soluble substances; for in the instance of the solution of oxide of arsenic, or of the bi-chloride of mercury (corrosive sublimate), which Kyan's solution is known to be, it is evident that any additional quantity of fluid coming in contact with it, will dilute it, or re-dissolve any of the salt which might have been deposited in the pores of the wood, by drying; the con |