PINAL 1 ICICIC, 
PARATISSOTIA, SPHENODISCUS. 
Figs. 1-3. Natural size. The venter is restored in fig. 1, and in fig. 3 the hollow 
keel is restored except in lowest volution of section, which is as seen 
in fig 4. 
4. Enlarged view of section of venter of lower whorl of fig. 3, showing 
hollow keel on its first appearance. 
5. Suture of first quarter of outer yolution of fig. 2; dorsal saddles merely 
indicated. : ; 
6. Much abraded sutures of last quarter of same, to show the number and 
general proportions of the curves; the ventral lobe is more deeply worn 
than the lateral. 
Cachiyacu, Peru; Upper Cretaceous; my collection. 
Hires: 7-15; Sphenodiscus pleunisepta (Conrad) 25-2 25222- 222222 e see ae ee ee Bey aaa sity 
Figs. 7-9. Natural size. Rio Pecos,(?) Tex.; Upper Cretaceous; Coll. Columbia 
University, New York, No. 10881. 
10, Enlarged center of fig. 9. The sutures in this were not so clearly seen as 
to make the observation in this and fig. 12 entirely reliable. 
11,12. Enlarged outlines of young of fig. 9. : 
13. Older specimen than figs. 7-12, showing the rounding of the venter. 
Near Eagle Pass, Tex.; U. S. Nat. Mus. Coll. No. 19145a. 
14. Loc. same, coll. same, No. 19145b. Same age as figs. 7 and 8, but showing 
more acute yenter and more prominent tubercles; this variation has 
been slightly increased by compression. 
15. Suture < 24 of specimen represented by Pl. V, fig. 3. Rio Pecos, (?) 
Tex.; Coll. Columbia University, No. 10881e. 
All on this plate are casts. 
258 
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