122 ' -'NAUTILUS. 



^so^4ftin{larger:at jt>itf?.end; but not margined: joints 

 eight'o'r nine, harclty Distinguishable, separated by straight 

 lines : aperture a little contracted, not oblique nor mar- 

 gined, with a small syphon : length about the tenth of an 

 inch. 



At Sandwich : very rare. 



18. Nautilus Radicula. Radicle Nautilus. 

 Montagu, pi. 6. f. 4, and pi. 14. f. 6. 



Shell oval-oblong or somewhat conic, straight, tapering, 

 smooth, brown, opake : joints varying from two to nine, 

 globular and very deeply divided ; aperture sometimes ex- 

 tended to a conical point, sometimes a mere small round 

 opening at the top of the primary joint : the smaller end 

 has also the joints compact and approximate, and some* 

 times the terminal joint is conical and pointed : minute. 



In fine sand. v. m. 



19. Nautilus subarcuatus. Crooked Nautilus. 

 Montagu, pi. 6. f. 5. 



Shell glossy-white, transparent, sometimes covered with 

 a brown skin, tapering and slightly curved, with three di- 

 stinct smooth globular joints, and numerous others which 

 are hardly conspicuous : aperture a small produced sy- 

 phon : the articulations or joints are sometimes to be num- 

 bered to the amount of ten : minute. 



In fine sand : very rare. v. m. 



* 



20. Nautilus costatus. Ribbed Nautilus. 

 Montagu, pi. 14. f. 5. 



Shell nearly cylindrical and straight, a little tapering to 

 an ojbtuse point, brown : joints twelve, sometimes only six, 

 raised and well defined, furnished with four equidistant 

 strong ribs running the whole length of the shell : aperture 

 ending in a short conic syphon : length above the eighth of 

 an inch. 



Variety A. Quite cylindrical, with five joints and seven 

 ribs, truncate at one end, the other terminating in a slen- 

 der cylindrical process as long as its annexed joint. Mon- 

 tagu, pi. 19. f. 2. 



Variety B* Quite cylindrical, with five joints and four 



ribs, 



