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V. Observations on Naticina and Dentalium, two Genera of Molluscous Animali. 

 By the late Rev. Lansdown Guilding, B.J. F.L.S. 



ReadJune 21st, 1831. 



The zoologists of the old school, regarding only the shells, have always 

 considered the Natkce as closely allied to the true Nerita; of Linnaeus, and 

 have obstinately retained them under the same generic title, rejecting all the 

 subgenera so properly instituted by modern writers. A very slight acquaint- 

 ance with the animals will convince us that the Naticidce form a distinct 

 family from the Neritidce, the two groups differing in many most important 

 characters. The former are apparently blind ; the operculum has no appen- 

 dages ; their useless tentacula are weak and turned back on the shell, while 

 in the act of creeping the head and its organs are perfectly veiled by a broad 

 expanded hood {cucullm), the sensitive contractile apex of which serves to 

 guide its motions. At first sight they rather resemble the Bidlidce than the 

 Neritidce : for these have prominent eyes, an exposed head and long projecting 

 sensitive tentacula, and the operculum has testaceous appendages for firmer 

 insertion into the foot. I have transmitted a drawing and description of the 

 typical species of Naticina to my friend Mr. Swaiuson, who has promised to 

 insert many of my drawings of West Indian shells in his beautiful work, 

 entitled " Zoological Illustrations." 



MOLLUSCA. 



Fam. NATiciDiE, Guild. Neritidae, Gray. 

 Genus 1. Natica, Guild. Naticae pars, Sowerhy. 



Character genericus. 

 Testa subglobosa v. obovalis, rarb depressiuscula. 



Spira brevis: apertura Integra, semiorbicularis, latere columellari obliquo, 

 edentulo, calloso. 



