GUDE : ON NEW GENERA OF ZONITID^. 391 



referred by various authors to Trochonanina or to Microcystis. For 

 this I propose the name of — 



Diastole/ nov. gen. 



Shell conoid, imperforate; whorls convex, angulate or keeled at the 

 periphery, finely striated, the base densely covered with microscopic 

 spirals ; the columellar margin provided with a tooth or callus. 



Tj'pe, Helix conula^ Pease. 



I would class the genus with Trochonanina; it is probably vivi- 

 parous, since in one of the species (cotiula) embryos were observed 

 inside the shells. The following species are included : suhcomda, 

 Pease; suhvenosa, Ancey ; angulifera, Mouss. ; Garrettiana, Aiicey; 

 and rectangula, Pfr. 



The last genus to be proposed is mouotypic — 



Advena,^ nov. gen. 



Shell depressed conoid, imperforate; whorls increasing I'apidly, 

 planate above, tumid below, keeled at the peripliery, coarsely and 

 unevenly ribbed or wrinkled above, the earlier ones with the ribs 

 decussated by about six spiral sulci which gradually become lost or 

 indistinct on the later whorls, the decussation descending below the 

 periphery and terminating rather abruptly, beyond which the base is 

 smooth and polished. 



Type, Helix Campbelli, Gray, from Norfolk Island and Phillip 

 Island. 



The present genus appears to me to have some affinity with Fijia 

 and Hemiplecta. 



1 5iaffTo\-fi, a difference. "^ A stranger. 



