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 oesophagus, 

 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 Jth 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, slightly 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- 



