PLATE XIII. GONIATITES CHOCTAWENSIS Shumard (p. 59). FIGURE 1. A narrow specimen of rather large size, without constrictions. Side view. 1a. Ventral view of same. 1b. Suture of same. 2. Side view of a small specimen with constrictions. 2a. Ventral view of same. 2b. Suture of same. 3. Side view of a young specimen. 3a. Ventral view of same. 3b. Suture of same, X 2. 4. Ventral view in outline of a very young specimen. 4a. Side view of same, in outline. 4b. Suture of same, X 5. 5. Suture about half a turn from the aperture of a mature specimen having a diameter of 25 mm. 6. Side view of a small testiferous specimen. 6a. Ventral view of same, showing the constrictions only where exfoliated, X 3. 6b. Ventral view showing aperture, in outline. 6c. Portion of the surface of the same. 7. Sculpture from the ventral surface of a specimen having a diameter of 12 mm. The crenulations show very faintly, but more than in figure 6c, where they do not show at all, X 5. 7a. Sculpture of same, near the umbilicus and about half a turn nearer the aperture, X 5. 8. Sculpture across the ventral surface of a specimen having a diameter of 6 mm. Constrictions show faintly upon the outside and are further indicated by intermittance of the sculpture. This figure may be compared with 6c, but the specimens are viewed in opposite directions, X 5. 9. Portion of the surface taken on the side of the shell of a specimen having a diameter of 18 mm., X 5. 10. Portion of a mature or possibly gerontic specimen, × 5. Originals of figures 1-10 from station 2083. 11. Ventral view of a specimen having a somewhat different expression and from a different locality from the foregoing. The difference in shape from figure 1a is not so marked in all cases. 11a. Side view of same. 11b. Sculpture of ventral surface near the aperture. (See 2a.) |