144 HELCIONISCUS. 



about l'^ to 14 irregular, rounded ribs. Spatula of an intense brown- 

 black, margined with white. (Angas.) 



Length '7, breadth "45, alt. -2 inch. 



Aldinga Bay, South Australia. 



P. latistrigata Angas, P. Z. S. 1865, p. 154, 186. 



H. GEALEi Angas. 



Similar to P. Jacksoniensis, but the interior splendidly metallic, a 

 little tinted with golden ; margin narrow. Spatula lurid, clouded 

 with leaden and brown. (Angas.) 



Length -1, breadth "86, alt. '4 inch. 



St. Vincent's Gulf, S. Australia. 



P. gealei Ang., P. Z. S. 1865, pp. 57, 186. 

 H. ARANEOSA Reevc. PL 71, figs. 57, 58. 



Shell suboblong-ovate, attenuated in front, rather thin, compressed 

 at the sides, apex rather sharply acuminated, anterior ; radiately 

 densely striated, striae corded, minutely crenulated with concentric 

 strise. Olive-green, conspicuously rayed with numerous opaque- 

 white lines. Interior semitransparent. 



A somewhat depressed species, pinched and sharply pointed to- 

 ward the apex, which inclines very much to the front, and of a dull 

 greenish-olive color, curiously rayed throughout with fine opaque- 

 white lines. (Rve.) 



Australia. 



P. araneosa Reeve, Conch. Icon., £ 111. March, 1855. 



Gould described in 1846 a different species under this name, but 

 it is probably an Acmcea. See appendix to this volume. 



(5.) Species of South and East Africa and adjacent islands. 



Limpets of the genus Helcioniscus are not found on the West 

 African coast, which is inhabited by the typical groups of Patella. 

 Upon the East African shores, however, typical Patella is not 

 numerous in si:)ecies, but Helcioniscus abounds from*the Red Sea to 

 the Cape. 



H. ROTA Gmelin. PI. 72, figs. 65-80. 



Shell oval, low-conical, the apex at the front third or behind it. 

 Sculptured with numerous subequal or unequal, obsoletely granu- 

 lous radiating strise. Outside whitish, having purple-brown rays 

 which sometimes branch to form v's, sometimes are spotted ivith light 



