8-1 TRUNCATELLIDJE. 



(as in the mysterious frontispiece that represents the 

 Domns Natures in ' Ripley revived/ by Eirenaeus Phi- 

 lalethcs) ; or perhaps the intermediate space is occu- 

 pied by exotic and fossil forms. At any rate I can place 

 the Truncatellidce nowhere else. The European seas 

 have only a single generic and specific representative, 

 which appears not to be found north of the English 

 Channel. 



Genus TRUNCATEL'LA* Risso. PL II. f. 2. 

 Generic characters those of the family. 



The habits of these mollusks are littoral. They live 

 chiefly on the brink of high-water mark, under stones 

 and decaying sea-weeds, which are periodically covered 

 by the sea ; and in this sense they may be termed am- 

 phibious. Considerable doubt has been entertained by 

 many naturalists whether Truncatella is marine or ter- 

 restrial, and whether it is furnished with gills like Lit- 

 torina, or with an air-pouch like Melampus. The careful 

 and long- continued experiments made by the Rev. R. 

 T. Lowe, which were published in the 5th volume of the 

 1 Zoological Journal/ seem to prove that it is truly 

 marine, one of his specimens having lived 14 weeks 

 constantlv immersed in sea-water : and Mr. Clark has 

 given us full particulars of the branchial apparatus. 



Lowe proposed at one time to call this genus Erjjeto- 

 metra (from its peculiar mode of creeping) ; Christo- 

 phori and Jan have given it the name of Choristoma, 

 Leach those of Zeano'e, Glaucotho'e, and (according to 

 Gray) Truncatula ; the young constitutes the genus 

 Fidelis of Risso. 



* Diminutive from truncatus, cut off. 



