NAUTILUS. 121 



14. Nautilus semilituus. 

 Montagu, pi. 19. f. 3. 



Shell opake, brown ; the six upper joints a little curved, 

 and each of them separated by a straight raised line ; the 

 lower-ones curling inwards, or sometimes nearly straight ; 

 the back margin with raised ridges at the division of the 

 joints : aperture a little contracted and rounded, with a 

 small syphon which is placed nearly in a line with the 

 outer margin : minute. 



In fine sand. v. m. 



15. Nautilus subarcuatulus. Hooked Nautilus. 

 Montagu, pi. 19. f. lJfalker, f. 73. 



Shell white, glossy, semitransparent, with twelve joints ; 

 the four or five primary ones nearly straight, and separated 

 by oblique raised and more opake lines ; the rest curling 

 spirally inwards, and divided by radiating lines ; the back 

 margin furnished with a raised ridge, and slightly indented 

 by the divisions of the joints ; the front margin obtusely 

 rounded : aperture oblique, with a small syphon at the up- 

 per point : length the eighth of an inch. 



Mr. Dillwyn, misled by Maton and Rackett, has united 

 these two last very distinct species, omitting Montagu's 

 figure of the first. 



In fine sand. v. v. 



16. Nautilus Legumen. Pod Nautilus, 

 Montagu, pi. 19. f. 6. 



Shell vrhite, smooth, glossy, transparent, somewhat flat- 

 tened, a little concave on one side, without marginal ridge 

 on either side, a little curved, slightly tapering or nearly of 

 equal diameter at both ends, the extremities of which are 

 a little rounded and contracted : joints eight or nine, divi- 

 ded by oblique lines ; the anterior or larger end oblique and 

 margined, with an obtuse syphon which rises above the 

 margin, and a considerable aperture near the concave side: 

 length above the eighth of an inch, 



In fine sand, v.m* 



17- Nautilus rectus. Straight Nautilus. 

 Montagu, pi. 19. f. 4, and 7 Walker, f. 74. 

 Shell brown, opake, thick, smooth, a little curved ai\d 

 w something 



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