CHITON. 249 
end ; above these are imbedded, in the margin and longitudinal 
area of the animal, eight transverse, convex, saddle-shaped, 
beaked, imbricated, strongly shagreened, dark grey testaceous 
plates, whereof the anterior one has five emarginations, the 
six behind in succession one on each side, and two on the 
terminal margin of the eighth. The head is a membranous 
puckered frill, under which is the rugosely-rayed buccal disk 
with its round orifice in the centre: there are neither eyes 
nor tentacula. The buccal apparatus consists of two elliptical 
white, or pale yellow corneous plates, between which a rather 
long, black, strap-shaped tongue passes, armed with a double 
line of tubercles, the inner edges being tricuspid; at the base 
of the corneous plates is a nervous collar of five minute sub- 
rotund yellow ganglions ; these are followed by the cesophagus, 
which leads into a complicated stomach doubled on itself, and 
is continued as an intestine of four or five folds, supported by 
the liver, which from their complexity can scarcely be de- 
scribed, as they lie in a space of little more than }th of an 
inch ; the last fold passes into a moderately long rectum that 
discharges in the centre of the branchial cordon ; the convolu- 
tions can be easily drawn out, and with the stomach, cesopha- 
geal canal and rectum, produce an extent of nearly 2 inches 
in moderate-sized examples. The pale yellow, minutely gra- 
nular, sinuated ovarium is immediately under the mantle, 
nearly co-extensive with the length of the body, and under it 
are the stomach and other organs, including the large liver of 
many granular dusky greenish-brown lobes. The foot is sub- 
oval, very little angular in front, shghtly tapering to an obtuse 
termination. The under part of the mantle is of a red-brown 
colour. Between the foot and mantle is the branchial cordon, 
composed of fifteen oblique, cord-like, short, close-set, pale 
brown fillets, on each side the body, commencing at the right 
and left of the immediate posterior extremity, leaving between 
the series only room for the depuratory duct ; the cordon does 
not quite extend half the length of the body; the fillets gra- 
dually diminish in volume from the posterior end, and at the 
anteal termination are not more than half the length or size 
of the hindmost ones. There are no traces of male repro- 
