553 
CENOCERAS GRANULOSUM. 
NAUTILUS GRANULOSUS, D’Orb. ( Zerr. Jurass., 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 (Vaut.) pseudoelegans, sp. D’Orb., which is found 
in the Necomian together with Cymatoceras neocomiense. Both of 
these have costz which pass entirely across the venter. Inthe type 
species these appear very late in the ontogeny in the ephelic stage, 
whereas in #eocomiense 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. (A@in. Conch., Pl. cxvi). 
NAUTILUS ELEGANS (?) D’Orb. (Zerr. Jurass., 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 
PROC. AMER. PHILOS. SOC. XXXII. 143. 3R. PRINTED JULY 19, 1894. 
