320 RODENTIA. 



along the wall of tlie large intestines for a short distance, diverging as they pass 

 downwards. These folds doubtless act in unison with the foregoing yalve, and 

 regulate the passage of the alimentary substances into the caecum. Between 

 these spiral folds a few large and solitary dark-brown glandular bodies are 

 scattered, and the apex of one is occupied by a puckering of the mucous 

 membrane. 



The pancreas is a long, almost filiform structure, nearly 2*50 inches in 

 length. 



The left segment of the liver in B. pruinosus consists of two lobes ; the left 

 lateral lobe is the largest and nearly twice the dimensions of the left central lobe 

 which it underlies, its right margin underlapping the right central lobe of the right 

 segment and abutting against the gall-bladder. It has a large auricular appendage. 

 The left lateral fissure is very deep, nearly cutting through the organ. The left 

 central lobe covers only one-half of the underlying lobe. The umbilical fissure is 

 deep on the under surface of the organ. A cystic fissure is slightly indicated on the 

 right central lobe, and the gall-bladder is small. The right lateral fissure is ex- 

 tremely deep, almost cutting off the right lobe of the right segment from its fellow. 

 The right lateral lobe is cut by a fissure, which runs as a deep groove along its under 

 surface. The Spigelian and caudate lobes are well defined. 



The liver also of B. hadius differs from that of B. pruinosus. The umbilical 

 fissure is rather shallow, and the left lateral does not completely underlap the left 

 central lobe. The gall-bladder is larger and lies at the base, but to the right of the 

 umbihcal fissure. The SpigeKan lobe has a long auricular process, and the caudate 

 lobe gives off a small secondary lobe. 



The heart of B. pi^uinosus is a rather elongated oval, with the left at a much 

 lower level than the right auricle, both of these cavities being rather small ; whereas 

 in B. badius the heart is more oblong than oval, the apex being broad and partially 

 bifid. 



The left lung is simple, but the right lung is deeply divided into four lobes. 

 The bronchial tube does not divide until it reaches the lung, and the bronchial 

 cartilages are either simple or bifurcated plates, not meeting in the middle line 

 posteriorly which is occupied by membrane. 



The vagina is one and a half inches in length, and its wall is smooth ; and the 

 two horns of the uterus open into its fundus by separate os tincce without the inter- 

 vention of any common uterine cavity, so that in this respect BMzomys conforms 

 to the uterine structure of the SciuridcE and LeporidcB, and not to that of the 

 MuridcE, The right horn in two examples — one of B. pruinosus and the other 

 of B. hadius — contained three embryos in the case of the former, and two in 

 the case of the latter. Two large rounded superficial glands lie on each side of 

 the vaginal orifice, and open at its lips, these orifices being marked by a long 

 pencil of hairs. 



In the male, the interval between the preputial orifice of the retracted penis 

 and the anus is 0*70 inch, and the testicles show on each side of this interval as 



