33 
TAB. XVI. 
MYTILUS stagnalis. 
Class 6. Vermes. Orders. Testacc:i. 
Gun. Char. Animal an Ascidia? Shell bivalve, 
rough, generally affixed by a beard of silky fila- 
ments ; hinge generally without teeth, with an 
awl-shaped excavated longitudinal line. 
Spec. Char. Shell ovate, rather smooth, gibbous, 
with a flat space near the hinge. 
Syn. Mytilus stagnalis. Linn. Syst. Nat. ed. 13.U.1. 
3362. 
Mytilus maximus planior viridescens edentulus. 
Schroel. Jlus conch. 159. t. 1 . f. 1 . 
The pair of shells from which these were drawn appear to 
he unique as British. They much resemble those of My- 
Ulus Cygneus, but are however more gibbous, and more 
pointed on one side. There is also a flat space near the 
hinge towards the broader side. The description, in Linn. 
Syst. Nat. ed. 13, which follows, agrees nearly with our 
shell, and we make no scruple of considering them as the 
same : — cc Like M. Cygneus, but the shell is much larger, 
being eight inches broad and four and half long, less con- 
' ex*, greenish, with obscure green rays, and the margin is 
yellowish brown.” In the copy of Schroeter at Sir Joseph 
This is the only part of the description which differs from our shell, which 
ls wore convex than M. Cygneus, 
V °L. I f D 
