CH^TOPLEURA. 31 



Central areas having subparallel or slightly radiating lines of 

 granules, about 20 on each side. Lateral areas scarcely defined, 

 having about 10 irregular radiating lines, the ant. valve having 50, 

 post, valve 40 such lines. Entire surface most minutely punctate. 



This species must not be mistaken for the externally very similar 

 Eudoxochiton. 



(2) Group of C. gemmea. 



C. GEMMEA Carpenter, n. sp. PL 13, figs. 69-74. 



Shell oblong, elevated, red, olive-ashen or yellow ; umbo of tail 

 valve depressed, situated behind the middle. Lateral areas decidedly 

 raised, coarsely radiately tuberculate ; central areas having longi- 

 tudinal beaded lirse. Girdle narrow, leathery, sparsely clothed with 

 short hyaline hairs, which are readily rubbed off. 



The valves are elevated. The central areas are sculptured with 

 elevated, distinctly beaded longitudinal cords, about 15 in number 

 on each side ; they became very small or subobsolete upon the 

 jugum. The lateral areas are strongly differentiated ; they have 5 

 to 7 radiating rows of distinct, clear-cut tubercles. The mucro does 

 not rise above the general level of the posterior valve. 



Inside often tinted with red, often having a red or black spot at 

 the jugal sinus. Sutural plates well-rounded, the sinus rather deep 

 and angular. Anterior valve having 9-12, median 1, posterior 

 valve 7-8 slits. Teeth rather blunt and stout ; eaves not spongy, 

 rather wide. 



Length 16J, breadth 8 mill. 



Monterey, California. 



ChcKtopleura gemmea CPU. MS. 



This beautiful little species is excessively similar to Ischnochiton 

 mertensii in sculpture, but the smaller size, narrower form, and 

 especially the short, transparent hairs of the girdle, distinguish it. 



C. BULLATA Carpenter. 



Shell subovate, elevated, olivaceous; intermediate valves ornamented 

 with strong rows of pustules; lateral areas very narrow, tubercu- 

 late, sometimes pustulate. Central areas having lines of tubercles, 

 about 7 on each side, and perpendicular lines, interstices granulated. 

 End valves having about 11 radiating rows of pustules; mucro 

 somewhat conspicuous. Girdle wide, having small hairlets. Sutural 



