NAUTILUS. 119 



lines are not visibly raised : aperture half heart-shaped, 

 very little clasping the body at the sides : minute. 

 In fine and drifted sand : v. m. 



6. Nautilus umbilicatulus. Perforated Nautilus. 

 Montagu, pi. 18. f. \ Walker, f. 69. 



Shell white, semitransparent, flat, perforated on both 

 sides : joints nine or ten, raised and rather rounded, marked 

 by radiating lines which are depressed : aperture clasping 

 the body nearly equally on both sides : minute. 



In fine and drifted sand. v. m. 



7. Nautilus crassuliis. Thick Nautilus. 

 Montagu, pi. 18. f. 2 Walker, f. 70. 



Shell strong, flat, opake, pale brown, with a deep perfo- 

 ration on both sides : joints numerous, close together, and 

 raised above the line of separation : aperture a little oblique, 

 hardly clasping the body, furnished with a syphon : minute. 



In fine sand. v. m. 



8. Nautilus crispus. Crimpled Nautilus. 



Montagu, pi. 18. f. bDorset Cat. pi. 19. f. 29 Walker, 

 f. 65. 



Shell white, opake, perforated both sides, with a keel- 

 like ridge on the outer edge : joints about twenty on the 

 larger volution, flexuous and crenate, and marked by raised 

 lines : aperture half heart-shaped, clasping the body, fur- 

 nished with a small central syphon. 



In fine sand. v. m. 



9. Nautilus Beccarii. Twisted Nautilus. 



Montagu, pi. 18. f. 4 Dorset Cat. pi 19. f. 28 Walker, 

 f.63. 



Shell transparent, white or covered with a brown skin, 

 crimson when the inhabitant is alive, convex on one side 

 and flat on the other: spires four or five, twisted, with ten 

 joints in the first which are deeply grooved : aperture ob- 

 oval : minute. 



Variety. With the spires reversed. 

 Montagu, pi. 18. f. 6 Walker, f. 64. 

 On oysters, and sea weeds, v. v 



10. Nautilus 



