162 PEBISSODACTYLA. 



standing one night it is often too much for the nose or eyes to stand 

 over it. It is from this circumstance perhaps that it is called in common 

 language, ' stale/ or that a horse ' stales.' 

 A mare has a hymen with two perforations 1 . 



Of an Ass \Equus Asinus, Linn. 2 ]. 



An ass, anatomically, is the same, or very nearly the same, as a horse. 



The oesophagus passes into the middle of the stomach : it is of no 

 great length helow the diaphragm, just like the human. The great 

 curve of the stomach is directly downwards, so that the oesophagus and 

 stomach make a pretty sharp angle. The stomach lies directly across 

 the spine from left to right : it is something of the shape of the human, 

 but is rather shorter and thicker: it is small in proportion to the 

 animal. In one ass the great curve lay directly towards the abdominal 

 muscles, which I suppose is the most natural position. 



The duodenum makes a pretty sharp turn downward on the right 

 side, before the right kidney 3 , as low as the brim of the pelvis ; it then 

 passes to the left across the brim, and begins to get a mesentery ; so 

 that it passes under the mesentery as in the human, but is not bound 

 down, for it is pretty loose. The ileum passes towards the right before 

 the turn of the duodenum that is going to the left: its muscular 

 fibres are very strong, and longitudinal; it dips into the caecum 

 eoli. 



The caecum is about 2 feet long, and very large, nearly 8 inches in 

 diameter : it is attached to a fold of colon nearly its whole length by a 

 thin mesentery about 3 inches in breadth, so that its direction is [that 

 of] the first fold of the colon. It has four ligaments, two of which 

 run into one near the blind end, and are not continued into the liga- 

 ments of the colon. The attachment to the colon is at one of the 

 ligaments. At the part where the caecum and ileum communicate with 

 the colon, the colon and caecum make a turn upon themselves : then 

 the colon makes a fold upon itself for near 5 feet in length, the bends 

 of which fold are closely connected to one another at their beginning, 

 but towards the retrograde end they are about 5 inches distant. The 

 beginning of the fold, or that which the ileum enters, is smaller, being 

 about 3 inches diameter, and increases to near the turning end, and 

 then becomes smaller, nearly as before, and some way after it has turned 

 it becomes large again, on to the place where it first set out ; the two 



1 [Hunt. Prep. No. 2840. One of the nipples of a mare is shown in Hunt. Prep. 

 No. 1409 ; and the position of both on the preputium clitoridis in Nos. 3749, 3750.] 



2 [The skeleton is No. 3216, Osteol. Series.] 



3 [The structure of the kidney is shown in Hunt. Prep. No. 1208.] 



