112 POLYPLACOPHORA. 



ment rather wide, black, covered throughout with brown hairs. 

 Length 22, width 14 mill. (Rochebr. in Bull. Soc. Philom. 1881- 

 '82, p. 193). 



Central America. Not common. Paris Mus. 

 Seems to be a true Chcetopleura. 



CHCETOPLEURA VENERIS Rochebr. Shell ovate, carinated; sooty ; 

 anterior valve radially ribbed, the ribs wide, lacunose. Posterior 

 valve small. Intermediate valves having the lateral areas bicostate, 

 punctate. Central areas sulcate, the sulci imbricating, spinulose at 

 the sides. Marginal ligament wide, sooty, clotLed with white setae 

 Length 25, width 14 mill. (Rochebr. in Bull. Soc. Philom. 1883- 

 '84, p. 34). 



Panta Arenas, Patagonia (Mission Lebrun). Rare. Paris Mus. 



CHCETOPLEURA AHNNI Rochebr. Shell wide ovate, flattened, 

 obtusely carinated, bluish-violaceous clothed throughout with brown 

 striae. Anterior valve rounded, 10 ribbed; posterior valve small, 

 elliptical, subumbonated. Intermediate valves wide, the lateral 

 areas very narrow and smooth, bounded by beaded ribs ; central 

 areas concentrically lyrate and most minutely striated. Marginal 

 ligament wide, brown, clothed with long tawny hairs. Length (JO, 

 breadth 41 mill. (Rochebr. in Bull. Soc. Philom. 1883-'84, p. 34). 



Punta Arenas Patagonia (Mission Lebrun). Common. Mus. 

 Paris. 



This and the preceding belong to the genus Plaxiphora. Roche- 

 brune ignores them in his later publication on Cape Horn Poly- 

 placophora. 



SCHIZOCHITON HYADESI Rocliebrune. PI 14, figs. 6, 7. 



Shell elongated, strongly carinated, dull whitish-coerulescent. 

 Anterior valve smooth, with 8 radiating ribs; posterior valve nar- 

 row, behind longitudinally sulcated, subemarginate, smooth, radiately 

 bicostate. Intermediate valves having the median areas smooth, 

 ornamented with articulated lines ; central areas lineate-denticulate ; 

 lateral areas erect, isopleural, concentrically lineate, and strongly 

 unicarinate in the middle. Girdle dull roseate, with sparse silky, 

 shining hairs. Length 52, breadth 25 mill. (Rochebr. in Zool. 

 Cap Horn, p. 132, t. 9, f. 1, 1889). 



Terra del Fuego, in 20 meters. 



Evidently a Plaxiphora. 



