In _Chondropterygians_ (Fig. 55) the stomach is divided into a cardiac and pyloric portion, the former frequently terminating in a blind sac, and the latter varying in length. The pyloric portion is bent at its origin and end, and separated from the short duodenum (called _Bursa entiana_ in these fishes) by a valve; the ductus hepaticus and pancreaticus enter the duodenum. This is succeeded by the straight intestine provided with the spiral valve, the coils of which may be either longitudinal and wound vertically about the axis of the intestine, as in _Carcharias_, _Galeocerdo_, _Thalassorhinus_, and _Zygœna_, or they may be transverse to that axis, as in the other genera. The number of gyrations in the latter case varies: there may be as many as forty. The short rectum passes into a cloaca, which contains also the orifices of the urogenital ducts. Only the commencement and end of the intestinal tract are fixed by mesenterial folds. In the _Holocephali_ and _Dipnoi_, the intestinal tract is short, straight, and wide, without stomachic dilatation, a pyloric valve, close to which the ductus choledochus enters, indicating the boundary of the intestine proper (Fig. 57, _p_). The spiral valve is perfect, and makes from three (_Chimæra_) to nine (_Ceratodus_) gyrations. A cloaca is present, as in Chondropterygians. A mesentery fixing the dorsal side of the intestine is absent. [Illustration: Fig. 55.--Siphonal stomach and spiral valve of Basking-Shark (Selache). (After Home and Owen.) _a_, Œsophagus; _b_, Cardiac portion of stomach; _c_, pyloric portion; _d_, pouch intermediate between stomach and duodenum, with circular valves at both ends; _e_, Duodenum; _f_, Valve of intestine; _g_, Ductus hepaticus; _h_, Spleen.] The other _Ganoids_ resemble again more the Chondropterygians in the structure of their intestinal tract. The stomach has always a distinct pyloric portion, and has a still more complicated structure in _Acipenser_. The duodenal portion receives the contents of _Appendices pyloricæ_, which are confluent into a gland-like mass in _Acipenser_, but separate in _Polyodon_, and numerous and short in _Lepidosteus_, whilst _Polypterus_ possesses one such appendage only. A spiral valve is developed in the Sturgeons and Polypterus, but in _Amia_, in which the intestine performs several convolutions, the four gyrations of the valve are situated far back towards the end of the intestine. In _Lepidosteus_ the valve is rudimentary, and indicated only by three raised lines crossing the terminal portion of the intestine. In all these Ganoids the rectum has a separate opening, without cloaca.