FAMILY 1. FISSURACEA, 21 
PARMOPHORUS, De Blainville. 
Testa oblonga, depressa, clypeiformis, superne convexiuscula, extremi- 
tate anticé sinu parvulo emarginata ; vertice minimo, postice in- 
flexo. Impressio muscularis canali ad sinum decurrente. 
The peculiar flatness which characterizes the shell of the Patella am- 
bigua of Chemnitz induced De Montford to select it as the type of a new 
genus, which he distinguished by the title of Seuta. This appellation 
was, however, changed by De Blainville to that of Parmophorus, and as 
he was the first to discover the true cervicobranchiate nature of the ani- 
mal, it has been generally adopted. Both Sowerby and Deshayes refuse 
to sanction this genus ; they consider that the Parmophori are too closely 
allied to the Hmarginule to admit of their being separated ; we must, how- 
ever, remember that, although the animals of the two genera are com- 
paratively alike, the typical species of each have very differently formed 
shells. In the Parmophori the shell is nearly flat, and merely indented 
at the edge with a kind of sinus; whilst in the Emarginula the type is 
very deeply conical, and exhibits a distinct longitudinal slit or fissure. 
The shell of Parmophorus may be described as being oblong, depressed, 
rather convex, shaped like a shield, and emarginated on the anterior side; 
the vertex, which is very small, is bent backwards. The muscular im- 
pression is interrupted anteriorly, and exhibits the mark of a canal run- 
ning to the marginal sinus, 
Kaamples. 
Pl. CXXXIX. Fig. 1. 
Parmopnorus corruGaatus, Nobis, Proceedings Zool. Soc., 1842. 
Pl. CXXXIX. Fig. 2 and 3. 
ParMopnHorus AusTRALIS, Lamarck, Anim. sans vert., old edit., vol. vi. 
2nd part, p. 5. 
