444 Mr. W. Clark on the Conovulidse, 



sillon anterieur est plus profond, et les carenes qui le bordent 

 sont plus accusees. Le bord posterieur de la face superieure est 

 surbaisse. Gault de Warminster, Blackdown ; Cr. tuf. de Beu- 

 zeville (Calvados)/' 



7. There are specimens of a Cardiaster from the greensand of 

 Warminster in the Museum of Practical Geology, identical with 

 the Spatangus fossarius of Miss Benett, distinct from C cor- 

 difurmis, and in all probability identical with the " Holaster 

 Greenoughii " indicated by Agassiz. 



8. A small species from the lower chalk of Dover, to which I 

 have given the name of Cardiaster pygmcms. 



The genus Cardiaster will be fully illustrated, and the species 

 C. cordiformis and C. excentricus figured in detail, in the 

 ' Figures and Descriptions of Organic Remains,' published by 

 the Geological Survey of Great Britain. 



XXXIX. — On the Conovulidse, Tornatellidse, anc? Pyramidellidse. 

 By William Clark, Esq. 



To the Editors of the Annals of Natural History. 



Gentlemen, Norfolk Crescent, Bath, Oct. 19, 1850. 



The small family of the Conovulidce, made up of the genera 

 Conovulus, Carychium and Acme, with very few species, and the 

 still smaller one of the Tornaiellidce that has only one species, in 

 point of natural order follow the Bullidce and HeliddcE ; with the 

 lateral intervention of the Littorinida, Trochidce, Cerithiada and 

 Turritellida:, they precede and introduce us to the numerous and 

 important family of the Pyramidellidee. As it is no part of my plan 

 to enter elaborately on the land and freshwater Mollusca, I shall 

 confine myself to the simple statement, that Carychium and 

 Acme only contain terrestrial pulmonifera; nevertheless the po- 

 sition of the eyes of the animals of these genera shows that they 

 are decidedly in conjunction with Conovulus, though they may 

 difi'er with each other in some specialties, the avenues to the 

 singular and well-characterized groups of the Pyramidellida, the 

 grand generic distinctions of which consist in the short trian- 

 gular basally conjunctive tentacula, with the eyes of the animal 

 imbedded at their internal bases. I should also have refrained 

 from mentioning Conovulus, if it was a well-determined fact, that 

 it had the respiratory apparatus of the terrestrial pulmonifera ; 

 but as some doubts still exist on this point, and having given 

 one of its species a rigorous examination, I think it will be ac- 

 ceptable to malacologists to review my notes, and form their own 

 judgement on the long and much-disputed point, whether the 



