32 The Rev. L. Guilding on Naticina and Dentaliiim, 



having been contracted from immersion in spirit, did not enable him to com- 

 plete his history of the animal, and it is probable much will remain to be 

 noticed till we can obtain the inhabitants of some of the larger shells. Having 

 lately dredged up a small specimen about -rs-ths of an inch long, I hastened to 

 make a highly magnified figure of it before its death, and my trifling addition to 

 the memoir of M. Deshayes is now offered to the Linnean Society, not without 

 the hope that my description may soon be rendered more perfect by the aid of 

 larger specimens. The minuteness of the example I obtained did not allow 

 me by dissection to ascertain many particulars recorded in the memoir alluded 

 to. The head, jaws, mouth, and lips, the museidar ring of adhesion, the anal 

 funnel-shaped expansion, and the horse-shoe cicatrix on the shell, escaped my 

 notice. What M. Deshayes has described as the liver, I should rather suppose 

 to be the branchiae, notwithstanding their unusual livid colour. These organs 

 are regularly and deeply pectinated, and resemble a long-handled comb. Tlie 

 numerous elongate subcapitate anterior organs I would call tentacula: their 

 extremities appear to be suctorious. Whether the convex side is properly called 

 the back I did not determine ; my specimen certainly drew itself along on its 

 side, but this may have been owing to the shallow layer of sand in which it 

 endeavoured to bury itself in the soup-plate which contained it, where it might 

 not have been able to assume its proper attitude. From residing under the 

 loose sand, their shells are of course free from extraneous matter, though not 

 shielded by the pallium. The creature moves tolerably quick by sudden in- 

 terrupted steps. When disturbed, it retreats quickly into its shell, which has 

 no operculum as the Serpitlidce. After a time the cloak is protruded, the ten- 

 tacula set in motion, and the vermiform active foot partially thrust out to 

 explore its path, as at Tab. III. fig. 1.: when it wishes to proceed apace, the foot, 

 with its petal-shaped alae closed round the stem, is protruded to its full length, 

 as at fig. 3. : the alae are then suddenly expanded, as at fig. 4. ; and the base 

 of the foot being forcibly contracted, the shell is brought forward, while these 

 expansions laid open in the sand prevent the apex of the foot from losing its 

 advanced position. In drawing up descriptions, we must be careful how we 

 speak of the absence of the anal fissure or rima. In recent specimens the apex 

 is often produced to a very fine thin point, which with the whole fissure is 

 very easily worn off, and seldom likely to occur in fossil examples, or shells 



