340 NAUTILUS. 



Inhabits ditches in Denmark. Muller. In Kent and about 

 London. Montagu. 



Shell near a quarter of an inch in diameter, brittle, pellucid, 

 polished, horn-coloured, or reddish brown, and appearing 

 black whilst inhabited by the animal, with three or four 

 curved white lines radiating from the umbilicus to the mar- 

 gin, and which are supposed to be the internal partitions ap- 

 pearing through the shell. 



calcar. 4. Shell with raised joints on the whirls, 

 and the aperture linear. 



Nautilus Calcar. Lin. Syst. Nat. p. 1162. Gmelin, p. 



3370. 

 Le Nautile microscopique epineux. Favanne, i. p. 729. t. 



7. f. B 3. 

 Gualter, t. 19. f. C. Martini, i. t. 19- f. 169, and t. 20. f. 

 182 and 183.? 

 Variety. Shell without spines. 



Le Nautile miscroscopique uni. Favanne, i. p. 735. t. 7. 



f. B4. 

 Gualter, t. 19. f. B. Martini, t. 19- f- 168. 

 Inhabits the shores of the Adriatic. Linnccus. 

 Shell minute, white, shining, somewhat pellucid, with a com- 

 pressed sharp keel, which is armed with four pointed teeth 

 at nearly equal distances from each other, and formed by a 

 projection of the dissepiments. Martini has considered his 

 figures 182, 183. to belong to the same species as fig. 169- 

 but Mr. Montagu in his Supplement, p. 76. suspects that 

 they are distinct. Da Costa says, that thirty-three of these 

 minute Nautili hardly equal a grain in weight. 



rotatus. 5. Shell spiral, smooth, keeled ; joints 

 six, with the partitions elevated andflexuose; 

 keel entire, aperture semicordate. 



Nautilus rotatus. Maton and Racket, in IAn. Trans, viii. 

 p. 114. 



Nautilus Calcar. Montagu Test. p. 189. t. 15. f. 4. Supp. 

 p. 76. 



Ptancus, t. 1. f. 3. Martini, i. t. 20. f. 180 and IS I. 

 Inhabits the shores of Rimini. Martini. England. Montagu. 

 Shell minute, smooth, spiral, with six joints on the body-whirl, 



marked by as many rlexuous elevated strias radiating from 



the umbilicus, but not quite extending to the margin. Back 



strongly carinated. 



