160 OBSERVATIONS ON THE CHAROPIDiE, 



rounded ; aperture subrhomboidal or securiform ; peristome thin, 

 simple, straight ; parietal region with one or two, and the palate 

 with (rarely without) two or three, internal laminae ; columella 

 emarginate and furnished with a spiral fold." 



Another genus which, judged by shell characters, would be 

 assigned to the Charopidce is Diplomphalus, Crosse and Fischer 

 (1872), described Journ. de Conch, xx. p. 288, type D. cabriti, 

 Gassies. The anatomy of this form as elucidated by Fischer 

 (Journ. de Conch, xxi. pp. 1-25, pi. in.) demands for it, on the 

 contrary, a position among the Testacellidce. Fischer suggests 

 {op. cit. p. 13), that various members of the Testacellidce, represent 

 different groups of the Helicidm, just as sundry orders of mono- 

 delphous mammals are shadowed forth among marsupials. We 

 might pursue the idea further and inquire whether the Testacellidce 

 may not be an artificial group composed of forms of diverse origin 

 which have independently acquired similar secondary characteris- 

 tics consequent on adopting carnivorous habits. If Diplomphalus 

 possesses a caudal mucous gland and pedal groove, these would 

 support the shell characters in claiming for it a derivation from 

 some form allied to Charopa. 



Under Charojndce, Hutton ranges (Trans. N.Z. Inst. xvi. p. 200) 

 these four genera : — 



Gerontia, Hutton (1884). 



" Shell depressed, widely umbilicated, striated ; periphery 

 rounded ; whorls about five, slowly increasing ; aperture oblique. 

 Mantle included. Jaw smooth, striated." 



First species (type f) G. pantherina, Hutton. 



Pyrrha, Hutton (1884). 



"Shell thin, translucent, of 4i-5|- regularly increasing whorls, 

 subperforate. Animal heliciforra, ■ mantle subcentral, reflected 

 over the peristome with an even margin ; tail truncate, with a 

 large papilla and mucous gland. Jaw with flat ribs. Marginal 

 teeth broad, with several points." 



First species (type 1) P. cressida, Hutton. 



