NAUTILUS. 343 



the surface varies considerably, being either smooth, striated, 

 ribbed or tuberculated. In the figure the joints are repre- 

 sented to be very numerous, and there is the appearance of a 

 broadish keel, but it is not mentioned in Schroeter's de- 

 scription. 



crassulus. 11. Shell spiral, compressed, umbili- 

 cated ; joints numerous ; aperture rather ob- 

 lique. 



Nautilus crassulus. Walker's Min. Shells, t. 3. f. 70. 

 Adams's Microsc. p. 6"41. t. 14. f. 35. Montagu Test. 

 p. 191. and Supp. p. 79. t. 18. f. 2. Maton and Rack- 

 ety in Lin. Trans, viii. p. 117. 

 Inhabits the sea shore at Reculver, in Kent. Walker. 

 Shell very minute, and is described by Mr. Montagu to be 

 strong, opake, pale brown, with numerous close sub-elevat- 

 ed joints ; sides compressed, similar, umbilicated, shewing part 

 of the interior volution within the umbilicus ; mouth placed 

 a little oblique, scarcely clasping the body-whirl, and fur- 

 nished with a Syphon. 



umbilicatulus. 12. Shell spiral, umbilicated on 

 both sides, with nine or ten joints projecting 

 at the partitions. 



Nautilus umbilicatulus. Walker's Min. Shells, t. 3. f. 69- 

 Adams's Microsc. p. 641. t. 14. f. 34. Montagu Test. 

 p. 191, and Supp. p. 78. t. 18. f. I. Maton and Racket 

 in Lin. Trans, viii. p. 115. 

 Inhabits the sea at Sandwich. Walker. Often forms part of 

 Sabella Penicillus at Kingsbridge, in Devonshire. Mon- 

 tagu. 

 Shell very minute, not half so large as N. crassulus, from 

 which Mr. Montagu says it differs in being somewhat hya- 

 line, in having the partitions less numerous, and the joints 

 becoming occult after a single turn, whereas in N. crassulus 

 the volution does not terminate at the mouth, and become 

 lost, but part of the second volution is visible beyond the 

 junction of the first, and is gradually lost in the umbili- 

 cus. 



lobatulus. 13. Shell spiral, rather flat, warty, 

 with very thin semilunar partitions. 



