ZOOLOGY. MOLLUSCA. 189 



Emarginula pileum. PI. 17, fig. 6. 



Shell elevated, with the form of a Phrygian cap ; apex largely 

 posterior, well beaked ; radiating lines alternate, deeply im- 

 pressed by the concentric lines of growth, and appearing 

 knobbed. Fissure moderately long, parallel-sided, and oc- 

 cupying the position of one of the larger ribs. 



Length slightly exceeding a quarter of an inch; height .2 inch. 

 Cseoum termes. PI. 17, fig. 5. 



Shell arcuate, gradually increasing in size anteriorly, where 

 it is somewhat swollen; surface longitudinally costated, the 

 costse appearing slightly rugose near the swollen base through 

 the passing of the lines of growth. Mucro distinct, well 

 excentric. 



Color of shell yellowish ; surface glossy. 



Length, about .1 inch. 



This form appears to be fairly abundant. It may be readily 

 distinguished from most of the other longitudinal costated 

 species by the very nearly equal diameter of the shell, which is 

 only slightly swollen basally. 

 Chama Benuudensis. PI. 17, fig. 1. 



Shell thick, ponderous, sub-cordiform ; the right valve con- 

 siderably smaller than the left, but yet thicker and deeper 

 than in most Chamas ; beak of left valve prominent, spirally 

 incurved ; ligamental furrow in left valve deep, arciform ; den- 

 tal sulcus broad, moderately deep, and supported inferiorly by 

 a prominent plate tooth. 



Muscular impressions elongated, not deep. External sur- 

 face roughly corrugated by the lines of growth. 



Height of shell (left valve), measured to the top of beak, 

 about three inches; length, measured along the antero-pos- 

 terior axis, 2.3 inches; thickness of single valve 1.2-1.5 inch. 



Dredged in large quantities in Harrington Sound. 

 Uacoma eborea. PI. 17, fig. 2. 



Shell moderately inequilateral, truncated in the lower half; 



