120 K. J. JBush — Jfarine Gastropods referred to 



Cirsonella Angas, 1877. Type, C. mtstralis Angas. New South Wales. 



"Shell minute, globosel}' turbinate, smooth, narrowly umbilicated; 

 aperture circular ; peritreme continuous, slightly thickened." 



Type, C. australis Angas. 



" Shell globosely turbinate, narrowly umbilicate, semi-opaque, 

 smooth, shining, white ; whorls 4, convex ; the last large, rounded at 

 the periphery ; aperture circular, peritreme continuous, slightly thick- 

 ened on the columellar margin. Alt. 1 line, breadth, 1 line." P. Z. 

 S., p. 38, pi. V, f. 16, 1877. 



Mr. Angas placed this genus provisionally among the Trochidae. 

 The " slightly thickened " as given for the peritreme in the generic 

 description is rather misleading, as it is definitely stated in the 

 description of the type to be " on the columellar margin." 



At ray request Mr. Smith has very courteously examined the type 

 which is in the British Museum. The following is an extract from 

 his letter under date of May 7th: 



" We have the type of Angas' Cirsonella australis, and it is placed 

 at present in the neighborhood of Ethalia. 



" It is a very minute, but solid, porcellanous shell, narrowly um- 

 bilicate, smooth, with a circular mouth, continuous double peristome, 

 the inner edge looking as if it might support a shelly operculum as 

 in Bithynia. The upper figure in P. Z. S., 1877, pi. v, f. 16, is a 

 good representation of the shell generally ; the figure of the under- 

 side is out of drawing and does not give the idea of a round aper- 

 ture and continuous lip. From its texture and general aspect I 

 think it may be left in its present location. Some of the small 

 Ethalias approximate rather closely to it, but their peristomes are 

 not quite so markedly continuous," etc. 



The open umbilicus w^ould, however, exclude it from Ethalia in its 

 restricted sense, so that the j^roper relations of the genus are still 

 doubtful. In outline, form of aperture, continuous peritreme, and 

 small umbilicus, it strongly resembles Lissospira Bush, (p. 129,) but 

 with the exception of L. ( Ganesa) rarinota Bush, the species of 

 that genus have shells of delicate texture and not at all solid and 

 porcellanous. Its affinities may possibly prove to be such that the 

 subgenus trcrnesa Jeffreys 1883 (p. J 14) would become synonymous. 



Dillwynella Dall, 1889. Type, D. modesfa Dall. Off St. Lucia, 226 fathoms. 



" Shell resembling Diloma in form, but minute, depressed, porcel- 

 lanous, wnth a thin, horny operculum of comparatively few whorls; 



