14 INTESTINE AND DIET OF REPTILES. 



the beginiiing part of the small intestine and tlie liver. Tlie 

 small intestine is laid in a nuraber of short and rather close 

 coils on the dorsal side of the median half of the ventriele 

 and then opens into a very capacions colon. The mucosa of 

 the small intestine is longitudinally plicated and the length 

 of tlie organ is aboiit 390 mm. The small intestine opens on 

 the ventral side and nearer the left (or median) side of the 

 colon. This latter together with the coecum forms a wide 

 säck of a flattened but roundish shape. In the specimen at 

 hand it measnres abont 7^/2 cm. across from right to left, 

 about (i\'2 cm. in anteroposterior and 3 cm. in dorsiventral 

 direction. The length of the whole large intestine ineluding 

 the coeco-colic säck is about 265 mm. From the right side of 

 this säck the continiiation of the large intestine leads back- 

 wards in a slightly undnlated course to the rectum and cloa- 

 cal apertnre. With regard to the situation of the opening 

 of the small intestine the ccecocolic säck can be said to form 

 right angles with the posterior continuation of the large in- 

 testine. The opening of the small intestine into the coeco-co- 

 lic säck projects like a powerful spout about 1 cm. in height. 

 The coeco-colic säck forms a single large cavity but just at 

 the bend where the continuation of the large intestine as- 

 sumes its backward course there is a large semilunar valve 

 measuring in the middle where it is highest about 3 cm. It 

 extends only along the posterior side of the lumen and is 

 situated on the median (left) side of the opening between the 

 two parts of the large intestine. That is thus just in the 

 bend and on its mesenteric side. Such a situation helps to 

 explain the origin of the valve itself. It is to be regarded 

 as having originated from the, in the bend, coalesced adjoining 

 walls of the two portions of the large intestine (conf. above 

 about Ägarna). These have first joined to form a limiting 

 lip and this has then grown forward and become better de- 

 veloped to form a valve. The dilatation of the coeco-colic säck 

 has also pressed its posterior wall more and more backwards 

 and thus helped in the formation of this pseudovalve. This 

 explanation of the origin of the colic pseudovalve of Uroma- 

 stix indicates that the latter organ is not homologous with 

 the colic valves found in the herbivorous Iguanids which are 

 described below. 



