152 



ZOOLOGY 



RROT. XII 



Fio. SIC— Kemiscyllium, pelvic arch and 

 pelvic fill. meUt, nietapterygium ; petv. 

 I'clvic arcli. 



bears only one large ray; the other two bear twelve or mon 

 rays, differently arranged in the two genera. 



The pelvic fin (Fig. 816) has only a single basal cartilage (meta. 

 articulating with the pelvic arch, with which also one or two of th( 



fin-rays articulate directly. Thi 

 peiv pelvic arch (pclv.) is a nearh 



straight bar of cartilage whicl 

 runs transversely across thi 

 ventral surface of the body, jus 

 in front of the cloacal opening 

 Enteric Canal (Fig. 817).- 

 The mouth leads into a ver 

 wide cavity, the pharynx, inti 

 which open at the sides the in 

 ternal apertures of the branchia 

 clefts and of the spiracle. Fron 

 this runs backwards a shor 

 wide tube — the oesophagus (ces. 

 — which passes behind into thi 

 stomach. The stomach is i 

 U-shaped organ, with a lonj 

 left limb continuous with thi 

 oesophagus, and a short righ 

 passing into the intestine. At the pylorus {pyl.) — the poin 

 where the stomach passes into the intestine — is a slight con 

 striction, followed by a thickening. The intestine consists of twi 

 parts — small intestine or duodenum, and large intestine. Thi 

 former is very short, only an inch or two in length. The latter i 

 longer and very wide ; it is divisible into two portions — the calm 

 (col.) in front and the rectum {red.) behind. The former is ver 

 wide and is chai-acterised by the presence in its interior of a spira 

 valve, a fold of the mucous membrane which runs spirally roun( 

 its interior, and both retards the too rapid passage of the food an( 

 affords a more extensive surface for absorption. The rectun 

 differs from the colon in being narrower and in the absence of thi 

 spiral valve ; it opens behind into the cloaca. 



There is a large liver (liv.) consisting of two elongated lobes. I 

 rounded sic — the gall-Madder (g. hi.) — lies embedded in the lef 

 lobe at its anterior end. The duct of the liver — the hile-duct (h. dct. 

 — runs from the liver to the intestine. Proximallyit is connectei 

 with the gall-bladder, and by branch-ducts with the right am 

 left lobes of the liver. It opens into the commencement c 

 the colon. 



The pancreas (pancr.) is a light- coloured compressed gland con 

 sisting of two main lobes with a broad connecting isthmus, lying ii 

 the angle between the right-hand limb of the stomach and th 

 small intestine. Its duct enters the wall of the small intestin 



