120 CAKTHARIDTIS. 



sutures distinct, impressed, the lower part of the last whorl nearly- 

 smooth, and the umbilicus white, smooth inside, the edge furnished 

 with a series of granules ; the mouth subquadrangular, outer lip 

 crenulated at the edge, columellar lip smooth, with a large tooth at 

 the inside and a little roughness on the outer side. 

 Axis 3-lOths, diam. 5-12ths of an inch. (Gray.) 

 M. denticulata Gray, in Capt. King's Survey of Intertrojjical and 

 Wedern coasts of Australia, ii, p. 479 (1827). 



M. RUDis Gray. 



Shell ovate, conical, imperforated, rough, pearly, concentrically 

 striated, whitish-brown; when worn or when eroded, purple; the 

 whorls convex, suture distinct, sometimes occupying an impressed 

 line on the lower whorl ; the base rather convex, the aperture 

 roundish, the axis (imperforate) covered with a white callous, which 

 leaves a slight concavity over its end ; the outer lip of three colors, 

 the outer part purple or green and white, the middle pearly, and the 

 inner opaque, white, and furrowed ; the surface of the lower part of 

 the last whorl is frequently worn away just opposite the mouth, so as 

 to leave a purple spot. ( Gray.) 



M. rudis Gray, in Capt. King's Survey of Intertrojjical and 

 Western Coasts of Australia, ii, p. 480 (1827). 



Genus CANTHARIDUS Montfort, 1810. 



Cantharidiis Montf., Conch. Syst., ii, p. 251 (1810).— H. & A. 

 Adams, Genera, i, p. 423. — Cantharis Fer. — Elenchus Swainsok, 

 Treatise on Malacol., p. 351. — Fischer, Manuel de Conchyl., p. 

 819. 



A genus restricted to Australasian seas, and hitherto found only in 

 shallow water. The radula shows several peculiarities in the forms 

 (Cantharidiis s. s. and Phasianotrochus) which have been observed ; 

 showing, probably, more affinity to G ibbida ih^w to any other genus. 

 In Cantharidiis (restricted) the centi-al tooth has a body with 

 broadly expanded supporting-wings, a narrowed peduncle or neck, 

 which bears a simple cusp. This peduncle has on each side delicate 

 wings, like those I have described for Phasianella virgo, and iden- 

 tical with those described and figured by Troschel for various species 

 of Giblnda. The lateral teeth number five on each side ; and they 

 increase in size from the inner to the outer one ; this peculiarity, 

 together with that of the central tooth just described, will enable one 



