H. Doc. 129. 27 



tincta, lineis radiantibus crebsis vix insculpta ; umbonibus eminent- 

 ibus obtusis ; extremitatibus rotundatis, rufo, biradiatis ; intus citrina, 

 sanguineo conspersa; margine argente crenulato. PL , fig. . 



Shell small, thin inequilateral, rounded ovate, moderately ventri- 

 cose, surface smooth and shining, with very delicate lines of growth, 

 and numerous, indistinct, radiating strise, more distinct posteriorly 

 and near the margin ; anterior and broadly rounded ; posterior end 

 narrowed, semi-rhomboidal, the dorsal mar gin rather rapidly declining; 

 color pale lemon, or straw-color, somewhat discolored or blotched 

 with rufous, the beaks biradiate with brown, and the posterior dorsal 

 area brownish ; interior bright lemon-color, beautifully stained with 

 dark liver-brown, especially near the beaks and posteriorly ; inner 

 margin minutely crenulated. Height and length five-eighths of an 

 inch ; breadth three-eighths of an inch. 



Locality. Inhabits San Pedro. Win. P. Blake. 



Compared with C. Elenense, Sowb., it is much less elevated and 

 differently colored, though the general characters are very closely 

 allied. It is more like C. Mortoni, Con., but is less solid, more inequi- 

 lateral, less truncate posteriorly and more freely colored within, and 

 the internal margin in that shell is not crenulated. 



TAPES GRACILIS, Gould. 



Testa parva, tenuis, inequilateralis, elongato-ovata, albida, obsolete, 

 fusco radiata, ad aream dorsalem posticam fuscata, concentrice, strio- 

 lata; extremitatibus rotundatis, extr. antico acutiore ; intus Candida. 

 PI. - fig. -. 



Shell small, thin, transversely elongate-ovate, rather compressed, 

 beaks, at the anterior third, whitish, with traces of dusky radiations 

 on the disks, and clouded with dusky or the dorsal areas ; surface 

 with very fine concentric lines of growth, coarser at the ends ; extrem- 

 ities rounded, the posterior somewhat obliquely, the anterior narrower 

 and somewhat more acute ; anterior dorsal area depressed, without 

 any line of demarcation ; interior white. 



Length three-fourths of an inch ; height half an inch ; breadth an 

 eighth. 



Locality. Brought from San Pedro by Mr. Blake. 



Belongs to the group with T. Florida and geographica, but in less 

 inequilateral and less angular than those shells. It may grow 

 much larger than the present specimen, and is pretty certain to vary 

 in coloring. 



' In addition to the preceding are two or three species left undeter- 

 mined in consequence of imperfect specimens, or because the characters 

 are not sufficiently marked to render their novelty decisive. The 

 following remarks may be added in regard to some of these : 



(1.) MYTILUS EDULIS, or very closely allied. It seems to differ in 

 having the dorsal angle at a greater distance from the beak the pos- 

 terior dorsal slope more rapidly declining and more curved, as in M. 

 hamatus the interior more pearly, and the margin more uniformly 

 deep black. 



Locality. San Francisco. W. P. Blake. 



