248 MR. G. E. DOBSON ON CAPROMYS MELANURUS. [Apr. 1, 



The Krer (Plates XIX. and XX. figs. 1, 1 «) differs from that of 

 C.jnlorides (Plates XIX. and XX. figs. 2, 2 a) chiefly in the absence 

 of that subdivision of the lobes into lobelets, as originally described 

 by Say and subsequently by Owen in that species, and as shown in 

 the figures above referred to. The primary division of the liver of 

 C. piloj-ides into lobes is, however, on precisely the same plan as in 

 O. melanurus, as may be seen by comparing the figures, the principal 

 difference in the general outline being noticeable in the right and left 

 central lobes, which in C. melanurus scarcely exceed the right and 

 left lateral lobes in length, but in C. pilondes are greatly produced 

 backward. In both species the Spigelian lobe («) is small and 

 similarly shaped, and in both there is a similar separated portion {l.l') 

 of the left lateral lobe {l.l). The gall-bladder is well-developed '. 

 The other abdominal viscera are as in C. pilorides. 



The epiglottis is short, and rounded at the tip. The vocal cords 

 are shallow, but very dense in structure, with sharply defined mar- 

 gins, as in C. jnlorides, but there are no distinct sacculi laryngis. 

 With this exception Prof. Owen's description of the larynx of C. 

 pilorides also applies to this species. The trachea is formed of twenty- 

 eight cartilaginous rings, dorsally imperfect ; the bronchi diverge 

 gradually, and the right bronchus much exceeds the left in calibre. 

 The lungs are divided into lobes precisely as in C. pilorides. 



The heart is rounded at the apex, without trace of a notch between 

 the ventricles. As in C. pilorides and Erethizon dorsatus ^ there is 

 a large innominate artery which gives off the right subclavian and 

 the two common carotid arteries, the left subclavian arising sepa- 

 rately from the arch of the aorta. The arrangement of the pre- 

 caval veins differs, however, remarkably from that of C. pilorides 

 as described by Prof. Owen, for instead of the blood returned from 

 the head and anterior extremities being emptied into the right 

 auricle by a single vein, there are, as in most species of Eodentia 

 and Insectivora, two precaval veins ; the left precaval vein receives 

 the left vena azygos and winds round the heart to open into the 

 right auricle, while between the orifices of the right and left preca\ ais 

 the j905^cawaZ vein enters. 



The male generative organs cannot be described for want of 

 material, but they probably resemble those of G. irilorides described 

 by Prof. Owen {I. c). 



The clitoris is provided with a long prepuce, and is perforated by 

 the urethra; the vagina is remarkably long and spacious, and its walls 

 are marked by numerous rugosities. The uterus (Plate XXI. fig. 4) 

 is bicornuate ; the long cornua unite by their internal margins in their 

 posterior thirds, but their cavities continue separate almost to the 

 vagina, into which, however, they open by a single os. Tiie ovaries, 

 as in the Hare, are not enclosed in peritoneal capsules, each capsule 

 is quite open, and the Fallopian tube, after pursuing a tortuous 



So diifei-iiig IVom Ercthison and tkix-olabcs, where there is no trace of one. 

 It must, however, be remembei-ed that there is a gall-bladder in the closelj- . 

 allied Hystrix. 



- Mivart, P. Z. S. 1882, p. 279. 



