ilN'M III I 



shaip, curiously marked by a long, narrow white line \\i,i, h , 



he accidental. ( 'flit I II I areas li:i\ 1! 



granulation! : falling invjuhirly into coi rin:at inn 



-rain-. Lateral aie;i- moderate! v rai- -I. \siili 



wrinkling pa.-.-ini: OVer about four very lilunt ob-ohte rib- : end 



Valves obsoletely radiated. Inieiior: posterior v:il\. 11, 



mitral \al\vs 1, anterior valve 1 -lit- ; teeth sharp, i.in ; 



sinus broad hut shallow, very -traiirln, -mo^th, not channelled ; 



eavee moderate, rather close to the teeth. Len-ih LI}, breadl 



mill. : divergence Id.". . 



I. CUIMIHVM - I'-. A. Smith. PI. L'l. li-. U lenlai 



Shell oval, llattish, of a dirty dark irravish color, havini: a 

 spictious black hroadish line from end to end do\vn the middle of 

 the hack, with a pale one on each side of it, and with the mantle 

 patched alternately li^lit and dark, irregularly granulated through- 

 out. Valvi-s arched, not carinate at the vertex, with verv indi- 

 lateral areas, exhihiting strong concentric lines of growth, e-pecially 

 conspicuous at the sides and anterior maririiis. Front plat*- well 

 curved anteriorly, the posterior margin beini: hroadly sinnat' d. 

 Second plate longer than the other intermediate valve-, sli-htly 

 incurved on each side, the central outcurved point in front, rather 

 peaked in the middle of the hinder edge. The third, fourth, fifth, 

 sixth and seventh valves are very short in comparison with their 

 width in proportion as 1 is to 3. The jngal sinus is large and arcu- 

 ate. Last valve of a narrow acutely elliptic form, with the n 

 prohably near the center. Interior of the plates greenish-hlue, 

 stained dark hrown in the middle. Lt'inina- of in>ertioii in tin- 

 front plate with about ten notches at unequal distance-, leaving 

 diflerent sized teeth between them, which an- ,-tiiated on both .-ides, 

 but more strongly externally, their edges being sharp, but not 

 smooth. The central plates have a single minute notch OH each 

 side, the insertion lamina being Comparatively Miiooth on the upper 

 surface and marked \\ith a small brown spot on each .-id 

 the edge of the valve. Tail plate much thickened \\itliin aloii. 

 posterior edge, which is roughened by fine crOSB stria-, th- 

 no prominent teeth, and of course no notches. .Mantle mar-in cov- 

 ered with small snbimbricating oval grannies. Length without 

 margin l(i mill.; width of fourth plate '.. 



