212 CLASS XV. 



The length of the intestinal tube in most reptiles is only twice 

 that of the body ; in the lizards it is about as long as the body, 

 if the tail, which is usually very long, be included ; sometimes the 

 length of the body, estimated in this way, surpasses that of the 

 intestinal canaP. The larvae of frogs and the land-tortoises, which 

 live on vegetable food, have the longest intestinal canal ; in these 

 its length surpasses that of the body three, nay even six times or 

 more. 



The boundary between the small and large intestine is often 

 indicated in reptiles by an annular membranous valve, or by a 

 coecal tube at the origin of the large intestine. This coecal tube, 

 which is almost never found in fishes, is wanting also in various 

 reptiles, in most batrachians, in many serpents, in the crocodile, 

 the turtles, &c., but still is present in many, especially in most of 

 the lacertine animals^. 



The reptiles have a cloaca or cavity in which are found the ter- 

 mination of the rectum, the aperture of the bladder, and those of the 

 ureters and oviducts or seminal ducts. Sometimes this cloaca is 

 to be regarded as a dilatation of the rectum. The anus or the 

 external opening of the cloaca is in the frogs and toads situated 

 behind on the back, in the tortoises sometimes under the point of 

 the tail. The opening is round or oval in the frogs and tortoises, 

 but in the serpents and most of the saurians is formed by a trans- 

 verse fissure luider the base of the tail. 



The liver is large in reptiles ; often it is not divided into lobes, 

 but only incised at the margin. In the crocodiles, however, in 

 the frogs and tortoises, the liver consists of two lateral portions, 

 sometimes quite distinct from each other and connected solely by 

 a duplication of the peritoneum, yet usually united by two or three 

 transverse strips. The liver receives a large quantity of venous 

 blood. In almost all (and the exceptions are not always constant) 

 there is a gall-bladder, which, however, is of less size than is 

 common in birds and mammals. Sometimes it lies hidden in the 



^ Comp. Cdvier Zej?. d'Anat. comp. ill. p. 457, ande ^d. iv. 2, p. 308. 



^ Comp. TiEDEMANN Ueber den BUnddarm der Ampkibien, in Meckel's Archiv 

 f. d. Physiol. III. s. 368 — 374, and generally on the intestinal canal in this class, a paper 

 of Meckel himself in the same vol. s. 199 — 232, with figures. On the intestinal tube 

 of serpents, see Duveenot Ann. des Sc. nat. xxx. pp. 128 — 155. 



