1 12 



rather wide, black, covered throughout with brown hairs. 

 th _>_>, width 14 mill. (Rochebr. in Hull. Soc. IMiilom. 1881- 



CentrcU America. Not common. Paris Mu.. 

 Seems to be a true Chcetopleura. 



CHCETOPLEURA VENERis Rochchr. Shell ovate, carinatcd; sooty ; 

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

 valve small. Intermediate valves having the lateral areas bicostate, 

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

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

 Length 2f>, width 14 mill. (Rochebr. in Bull. Soc. Philom. 1883- 

 '84, p. 34). 



Arenas, Patagonia (Mission Lebrun). Kan-. Paris Mus. 



CIKETOPLEURA AHNNi Rochebr. Shell wide ovate, flattened, 

 obtusely carinated, bluish-violaceous clothed throughout with brown 

 stria?. 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 GO, 

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



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

 Pfcris. 



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

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

 placophora. 



SCHIZOCHITON HYADESI Rochebruiie. 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,suhemarginatc, 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 thr middle. Girdle dull roseate, with ~i'ky, 



shining hairs. Length ^"2, breadth 2"> mill. (Rochebr. in Zool. 

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



Term del Fnego, in 20 meters. 

 lently a 



