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Cenoceras GRANULOSUM. 



Nautilus granulosus, D'Orb. (Terr. Jur ass. \ PL xxxv). 



Loc, Chatillon, France, Oxfordian. 



PL xi, Figs. 36-39, and Fig. 31, PL xii. 



In this species, which is well characterized by its compressed 

 form and tubercular ornamentation, the compressed form is present 

 even in the nepionic stage. Figs. 37 and 38 show that the umbil- 

 ical perforation is of medium size. Contact takes place on or near 

 the dorsal edge of the cicatrix on the apex, as shown in Fig. 31, 

 PL xii. The citatrix is plainly visible in several specimens of this 

 species and it is also obvious that in none of them does the dorsal 

 furrow appear until after the gyroceran bend begins. The dorsum 

 of the metanepionic substage remains rounded and gibbous until 

 the bending begins and then it becomes flattened and immediately 

 hollow, showing the commencement of the dorsal furrow as in 

 Figs. 36 and 37, and this continues to deepen and broaden through- 

 out the paranepionic, as is shown in Figs. 38 and 39. 



Cymatoceras. 



This genus, described in Genera of Fossil Cephalopods, had for its 

 type Cymatoceras (JVaut.) pseitdoelegans, sp. D'Orb., which is found 

 in the Necomian together with Cymatoceras neocomiense. Both of 

 these have costse which pass entirely across the venter. In the type 

 species these appear very late in the ontogeny in the ephebic stage, 

 whereas in neocomiense and other species the costations appear 

 earlier in the ananeanic substage. The sutures have slight ventral 

 lobes or saddles with deep lateral and dorsal lobes. There are 

 annular lobes at a very early age in some species. 



Cymatoceras elegans (?). ■ 



Nautilus elegans (?) Sow. (Min. Conch., PL cxvi). 



Nautilus elegans (?) D'Orb. (Terr. Jur ass., PL xix). 



Loc, Texas, Cretaceous. 



PL xii, Figs. 16-21. 



This species is represented by a number of specimens of the 

 young, but these do not break apart well and have to be cut and 

 viewed, as a rule, in sections. 



The large size of the apical chamber is noticeable, and the great 

 distance apart of the first sutures indicates the rapid growth of the 



