245 



Subgenus CALPURNUS, Montfort. 1810. 



Shell gibbous, subcarinated across the back, with at either 

 extremity a dorsal tubercle encircled by a groove, outer lip 

 dentate on the margin. 



Animal having a large foot, the mantle not tuberculate and 

 covering only a portion of the back of the shell. 



Apparently rather closely related/to Cyprsea, but the dentition 

 being unknown, its definite place remains uncertain. 



In addition to the above, the following fossil forms have been 

 described : 



TRANSOVULA, Gregorio, 1880. Shell oval, slightly rostrated, 

 lip denticulated, columellar margin crenulated. 0. Schefferi, 

 Eocene of Sicily. 



DIAMEZA, Deshayes, 1865. Shell elongated, mucronated be- 

 hind, lip sharp, aperture oblong, hardly narrowed in front. 0. 

 media. Desh. Eocene, Paris basin. Somewhat resembles Tere- 

 bellum. 



GISORTIA, Jonsseaume, 1884. Described as a group of Cyprse- 

 idse, but placed doubtfully under Ovula by Fischer. It includes 

 recent as well as Eocene species, and I think its affinities most 

 decidedly with Cyprsea, rather than with Ovula. 



Several monographs of Ovula have been published : 



L. C. Kiener. Coquilles vivantes, 23 species. 



G. B. Sowerby. Thesaurus Conchyliorum, ii, 1855, 48 species. 



Lovell Reeve. Conchologia Iconica, 1865, 66 species. 



H. C. Weinkauff. In Kiister's Conchylien Cabinet, 72 species. 



Also catalogues by : 



S. R. Roberts. Am. Jour. Conch., 1865, 72 species. 



II. C. Weinkauff. Jahrb. Malak. Gesell.. 1882, 66 species. 



The differences between Ovula and Cyprrea are carefully indi- 

 cated in a paper by Prof. Theodore Gill, entitled " On the rela- 

 tions of the Amphiperasidae," Am. Jour. Conch., vi, 183. 



