1380 PIJ-IODON 



Splendidly white and iridescent ; teelh irregular and continuing' 

 more or less throughout the hinge. 



Length 92, height 48, diani. 35 mm. 



I<ake Tang'anyika. 

 Camcronia hmdcaui BouRGinONAT, Un. and Tr.. t886, p. 74; 



Icon. Mai.. 1888, pi. xxxi, fig. 3. 

 Pleiodon laudcaiii Simpson. Syn., 1900, p. 909. 



Less elongate than P. spekii and having the dorsal line more 

 arched. 



PivEionoN BOURGUiGNATi ( 1 lourguiguat ) . 



Shell much elongated, very solid, inflated, inequilateral ; 

 beaks and umbonal region full, high and elongated; dorsal 

 and basal outlines lightly curved ; anterior and posterior ends 

 almost evenly rounded, the latter a little the wider ; surface 

 roughly, concentrically striate, almost black ; valves gaping" 

 at the anterior base ; nacre rosy white, brilliantly iridescent : 

 hinge plate wide and flat, having a few, irregular, strong, 

 nearly vertical teeth behind the beaks and three or four small 

 tubercles in front of them ; muscle scars large and deep. 



Length 130, height 51.5, diam. 48 mm. 



Lake Tanganyika. 

 Cameronia bourgui;.^nati Bourguignat, Esp. Ouk., 1885, p. 



26; Icon. Mai., 1888, pi. xxxni. 

 Pleiodon boit)\(^nignati Simpson, Syn., 1900, p. 909. 



Apparently a very good species. In outline it is almost 

 evenly long elliptical, the beaks are very prominent, the sur- 

 face black and the epidermis somewhat shaggy behind. Aery 

 solid, with a wide hinge plate and a few strong teeth. 



Credited to Ancey in lift, by Bourguignat. 



Plkiodon gtraudi (Bourguignat). 



Shell elongate-ovate, inflated, thick, solid, gaping anteriorly, 

 lightly striate, shining, blackish-brown, reddish-brown towards 

 the umbones ; dorsal margin straight, oblique ; anterior margin 

 rounded, somewhat cut away below ; basal margin slightly in- 

 curved ; posterior end extended in a very obtuse, rounded 

 beak ; umbonal region greatly inflated ; beaks very prominent,. 



