radiating sculpture, but ou the other specimen there are 

 16 distinct radii. The test is very thin, and there is a fold 

 or depression in the centre of both valves, which is absent 

 in S. compt-cssa. This depression reaches from the beak to 

 the ventral margin, and is removed from the anterior 

 extremity about one third of the length of the shell. The 

 ventral margin is not unbroken as in S. compvcsm, hut is 

 curved inwards to meet this fold, the posterior side of 

 which is occupied by the radii. There can be no possible 

 doubt that the two species are distinct. 



SoLENOMYA TRANSLINEATA, Sp. 110 V. 



Specific Characters.— Shell soleni forme, elongated pos- 

 teriorly, moderately thin ; posterior portion rounded on 

 both margins, and gradually narrowing to its extremity 

 whieh is also rounded. Anterior adductor impression small 

 and shallow, while the posterior impression is hardly visiUe. 

 There are two smaller linear impressions running parallel 

 to each other just anterior to the umbos. Dentition 

 obscure. On one cast a slight undulation is seen in the 

 infilling of the sub-umbonal portion of the hinge region, 

 representing an inflation in the lunge. The ornamentation 

 consists of numerous very fine radiating striae, covering 

 the whole surface of the shell. These are crossed by 

 regularly placed and fairly deep growth folds. The number 

 of striae counted within one half inch, measured in the 

 centre of the valve varied from 26 to 30. 



Dimensions— Length 1 ', Inches: height ,', inches; thiek- 



specimeus weiv obtained, l.oth as casts aim 

 matter preserved. This species approaches 

 de Kon., ,S. wgiitata, de Kon., from the Car- 



