210 PECTINIBRANCHIATA.—FISSURELLADZ. 
GENUS FISSURELLA. 
From the usual form of the orifice in the shell 
of this genus, which resembles that of a key-hole, 
the species are familiarly known by the appellation 
of Keyhole Limpets. Itis placed at the summit 
of the shell, which is very regularly conical, and 
not otherwise to be distinguished from that of a 
Patella. .In the very young condition the orifice 
is placed more forward. The animal has been 
already sufficiently described. 
We have but a single native species, the Netted 
FISSURELLA RETICULATA. 
Keyhole Limpet (Fissurella reticulata). It attains 
an inch in length, is of an oval form, and of a dirty 
white hue, with dusky rays. - Its surface is sculp- 
tured with a raised network, formed by radiating 
and circular ridges.. The animal is large, and of 
« yellow colour, varying in shade from cream- 
white to a rich deep orange; the latter hue being 
seen only in those specimens that are found ad- 
hering to shells incrusted with a scarlet sponge. 
It is obtained only on our western and southern 
coasts. 
