W1UGHT ON THE AXOLOTL. 63 



imperfectly figured in one of the Plates ;* when inflated, it is pyriform ; 

 in the empty condition, it assumes the outline of the liver (see Plate II 

 Fig. 3). The biliary ducts open into the intestine, just where it is 

 connected with the liver, by a common duct. 



The small intestines make two principal convolutions, and are kept 

 in their place by a well- developed mesentery. I could detect no trace of 

 a pancreas. As the intestine approaches the rectum, it becomes exces- 

 sively narrow, and at last ends almost by intussusception (Fig. 5) ; the wide 

 and capacious rectum ends in the cloaca. Before examining the internal 

 structure of these parts, it may be well to compare them with similar 

 organs occurring in the salamanders. For this purpose I have selected 

 Triton cr (status and Salamander maculosa. So far as the oesophagus and 

 stomach are concerned, the relative size and proportions are nearly 

 similar. The stomach is more pear-shaped in S. maculosa. In Triton, 

 the spleen is a small, flat, oval gland, attached to the right side of the 

 stomach by a loose fold of mesentery, but by no means closely so ; in 

 Salamander,! it is a long, narrow, ribbon-like body, closely attached to 

 the right side of the stomach. In Triton, the liver is small, but di- 

 vided into lobes; the gall-bladder is well developed. In Salamander, 

 the liver is rather small in proportion, not much divided, and the gall- 

 bladder is also small. In both Triton and Salamander, the small intes- 

 tine is very well developed, and in both does it contract as it approaches 

 the rectum, which here, as in Siredon, is much wider than the rest of 

 the intestinal canal. 



In the axolotl the oesophagus is short, the mucous surface is longi- 

 tudinally and finely striated, the external muscular fibres are circular, 

 and act as a sphincter; in the stomachy the mucous membrane is conti- 

 nuous with that of the oesophagus, but here it is thrown into deep folds. 

 The fine striae of the oesophageal portion are continued; and at what 

 may be considered as the cardiac orifice, these folds of the mucous sur- 

 face are brought into such close apposition, their dimensions at this spot, 

 too, are so greatly increased, forming four or five little protuberances ; 

 as to take the place of a valve and effectually prevent any regurgita- 

 tion into the mouth. Though there are a few file-like teeth in the upper 

 jaw, yet they serve more for organs of prehension, and cannot be of much 

 use in mastication; and, undoutedly, the process of comminuting the 

 food is mostly accomplished in the stomach. 



In this organ, as I have said, the mucous membrane which lines the 



*Loc. cit., Plate 12, Fig. 4. 



f Here I would observe, that I cannot agree'with Schneider, who, in his Natural 

 History of Amphibia, has united the aquatic (Triton) with the land (Salamander) 

 Salamanders ; although in both genera the ovjb are impregnated before being laid, yet 

 in the one (Triton), we have the eggs deposited on aquatic plants; the young Tritons, 

 when hatched, retaining their branchiae for a longer or shorter length of time ; in the 

 other (Salamander) we have the oviducts large and capacious, the ovae are hatched 

 in them, making their exit into the world almost miniatures of their parent. Surely 

 such embryological distinctions point to at least a difference in the general — in the ordi- 

 nary acceptation of this word — of these creatures. 



