35 



NAUTILUS Sowerbyi. 



TAB. DCXX\U.—Jig. \,2&3. 



Spec. Char. Lenticular, with a rounded edge, 

 umbilicated ; septa very convex, their ends 

 much recurved and obhquely truncated ; si- 

 phuncle very near the inner edge of the sep- 

 tum ; aperture triangular, longer than wide ; 

 lines of growth suddenly bent very far back- 

 wards. 



Syn. Nautilus Sowerbyi, fVeiherell in Phil. Mag. 

 andJourn.v. ix. 466. Morris, Cat. 1S3. 



One of the discoveries made by Mr. Wetherell in the 

 cutting at Chalk Farm for the Birmingham railroad, in the 

 middle part of the London Clay. It also occurs at Bognor, 

 as I learn from Mr. Dixon of Worthing, and I have seen 

 it from Sheppy. It is a well-marked species, which grows 

 to nine inches in diameter. 



Figs. 4, 5 and 6 are added to this plate to show the po- 

 sition of the siphuncle and form of the septum in each of 

 three other s})ecies of Nautilus. Fig. 4 is N. imperialis 

 (tab. 1), which has a somewhat triangular septum, wider 

 than long, with broad obliquely truncated sides which 

 are suddenly reflected, and a siphuncle that recedes from 

 the inner margin as the shell increases in size. Fig. 5,* 

 N. regalis (t. 355) : the septum rather square, no part 

 of it reflected, and the siphuncle nearly central. Fig. 6,* 



• In jornp copies thcsp ntinibcvR are accidcntalt}' reversed. 



