MUS DEOUMANUS. 231 



the extremity of the corn.ua and the ovaria. There were four foetuses 

 in the right cornu of this womb, and two in the left 1 . 



[Family MURIDjE.] 



Of a Rat \_Mus decumanus 2 ] . 



The arteries arise from the curve of the aorta just as in the human. 

 There are two venae cavse superiores. The contents of the thorax are 

 as in the squirrel. The trachea is bony ; the lungs are divided into 

 three lobes on the right side, besides the middle lobe, or that between 

 the heart and diaphragm : the left lung is one entire lobe, but would 

 seem as if it were two united by adhesion 3 . 



The oesophagus below the diaphragm is about \\ inch long, and has a 

 mesocesophagus ; and is inserted about the middle of the concave curve 

 of the stomach. The great arch or end of stomach is very long, and as 

 it were bent upon the oesophagus, or turned in upon itself, making a 

 common arch between it and the oesophagus 4 . All that part upon the left 

 of the oesophagus is of a whiter colour than the other externally, and 

 is thin ; having hardly any muscular fibres on it excepting the concave 

 side, and is lined with a kind of cuticle which is white towards the 

 small curve 5 : there is a tendon on each side, as in a bird, and all that 

 part that is between the oesophagus and pylorus is strong and mus- 

 cular ; it is soft and spongy upon the internal surface. The small arch 

 is attached by the mesogaster to the liver, but not on the same plane ; 

 for, about the middle of it, it makes an angle, by being inserted there 

 lower, or nearer the lower edge of the liver. Before the spine the 

 stomach ends in the pylorus ; thence, to the right, goes the duodenum, 

 which has a pretty long mesentery as it passes clown the right side ; it 

 then makes a turn to the left, and passes up by the side of the rectum 

 to the root of the mesentery : it is attached to the rectum by a narrow 

 membrane, and also to the root of the mesentery, as it passes forwards 

 round its left edge ; it then becomes loose and convoluted, and enters 

 the [part of the] colon which lies before the spine, and a little to the 

 right. The caecum is turned towards the right, is about 1| inch long, 

 a little bent, and near an inch in diameter. The colon at the insertion 

 of ileum is a little convoluted, as it comes out on the left of that inser- 



1 [Hunt. Preps. Nos. 3462 — 3465; showing the extensive vitellary sac, and the 

 small discoid placenta.] 



2 [The skull is preserved in the Hunterian Osteol. Series, No. 2234 ; the teeth are 

 displayed in No. 2235.] 



3 [Hunt, Prep. No. 1130.] * [lb. No. 447.] 5 [lb. No. 1908.] 



