15 
TAB. III. 
SOLEN affinis. 
Gen. Char. An equi valve, transversely elongated 
bivalve, gaping on each side, the hinge teeth, 
single in each valve or double in one valve. 
Spec. Char. Shell linear subarc uate, rounded at 
each extremity, hinge placed near one extremity, 
surface smooth. 
This Shell is about five times as broad as it is long, but 
slightly curved and very thin. 
It has been found plentifully imbedded in Marie septariae 
at Highgate. Its similarity to Solen pellucidus, which 
has occasionally been found recent in several parts of 
England, is so great that we at first considered it as the 
same species, but in the fossil the extremity of each valve 
farthest from the hinge is uniformly rounded, which is not 
the case with the recent species, that being squarish at the 
end ; this is, moreover, a rather straighter Shell. The 
teeth of the hinge could not be found in our specimens, but 
we suppose from the analogy of the greater part of the 
Shell, that they are like S. pellucidus. The sizes of both 
Shells vary, I have either from less than half an inch in 
breadth to above an inch, and of a proportionate length. 
They are of a darker or lighter horn colour. The fossil 
Shells are mostly placed in pairs. 
