HELCIONISCUS. 147 



area having an ill-defined callus, Avliich is more or less deeply stained 

 ivith bright gaviboge yelloiv. Length 40, l)readih 34, alt. 10 mill. 



M(ni7'itius. 



P. novemradiata Q. & G., Voy. de I'Astrol. p. 346, t. 70, f. 22, 23. 

 — P. aster Reeve, Conch. Icon. f. 80, 1855. 



A splendid species. The rays are broad and about nine in num- 

 ber, but more frequently they are twice as numerous by the splitting 

 of each broad one into two. Quoy & Gaimard described a very 

 young shell. Reeve figured under the name P. aster, a small speci- 

 men from an unknown locality. The series before me is from 

 Mauritius (Robillard Coll.). 



It is a much larger, more spreading and vividly colored shell than 

 the allied P. profunda. There is little besides coloring to sunder 

 this species from P. rota Gm. Compare also P. capensis and P. 

 variabilis, the former of which may be the same. It should be noted 

 that Gmelin refers to Kaemmerer, t. 2, f. 1, 2, as an" illustration of 

 his capensis. These figures represent the typical novemradiata. 



H. VARIABILIS Krauss. Pi. 16, figs. 18, 19, 20. 



Shell ovate, thin, depressed-convex ; whitish or ashen-yellow, 

 painted with radiating bands and spots of ashen or brown ; radiately 

 striated, striie or riblets unequal, transversely very viimdely striated; 

 vertex acute, looking forward, situated at the front third ; margin 

 denticulated. 



Interior yellowish, rarely whitish, having radiating bands and 

 spots of brown, shining. Central area not distinct, yellowish or 

 Avhitish. (Krauss.) 



Length 32, breadth 24, alt. 7-9 mill. 



' Natal. 



P. variabilis Krauss, Die Siidafric. Moll., p. 35, t. 3, f. 12 (not 

 P. variabilis Sowb., a species oi' Acmtea.) 



This is a flatter shell than the preceding, rather thin, translucent, 

 rarely eroded at the apex. The apex is more forwardly directed than 

 in P. capensis. From it many (70-80) alternately larger stride 

 radiate, which are cut by very fine concentric strijfi, scarcely visible 

 with the naked eye. The color outside is usually dirty white or 

 yellowish with many grayish-brown or brown radiating stri?e or 

 flecks, which are visible with more intense color through the gray- 

 ish-yellow or whitish-yellow shining (but never silvery and pearly) 



