108 CALTPTRiEID^. 



II — HIPPONYCIN^. 

 Genus HIPPONYX, Defrance, 1819. 



Shell thick, obliquely conical, non-spiral, apex somewhat pos- 

 terior and directed backwards, surface rugose or longitudinally 

 grooved or cancellated ; muscular impression horse-shoe shaped ; 

 base of attachment (opercular piece) when present, thick. 



Animal oval or suborbicular, conical or depressed ; foot very 

 thin, a little thickened towards the margins ; head globose, sepa- 

 rated from the body by a neck-like constriction ; eyes upon 

 swellings of the tentacles. 



Dentition, PL 30, fig. 6. 



Distribution : Warm seas. Fossil : Cretaceous, Eocene. U. S., 

 Europe. 



The synonj^ms are GochlolejDas, Klein, 1753; Krebsia, Morch., 

 and Amalthea. Schum., 1817. 



The same species will either excavate a cavitj?^ to which it 

 adheres, or secrete a testaceous support. The section Amalthea 

 was formed for certain species which were supposed to differ 

 from Hipponyx in not secreting a shelly base, but forming 

 instead a cavit}^ in the surface of shells. 



Genus MITRULARIA, Schum., 1817. 



Shell conical, more or less irregular with a subcentral, sub- 

 posterior, subspiral apex ; interior with a central, half cup-shaped 

 lamina, open in front, free on the sides, attached at the apex ; 

 basal plate thickened. 



Animal with broad muzzle, tentacles lanceolate, with eyes 

 externally near their base, the neck lobed on either side. 



Inhabits temperate and tropical seas, distribution world-wide. 

 The s^monymy includes Cemoria, Risso; Mitrella, Trochilina, 

 Trelania and Poculina, Gray, 1867 ; Lithedaphus, Owen, and 

 Galyptrsea, Lam., 1801, not 1799. Lamarck at the later date 

 adopted for his type a species belonging to the present group to 

 which it has since been generally applied, whilst the name of 

 Galerus.^ Humphrey, has been the received designation for the 

 CaZ?/p<r«a, Lam., of 1799. I follow Dr. Fischer in correcting 

 this matter, and like him displace the earlier but ill-founded 

 name of Humphrey for the latter. 



