484 MR. G. W. BUTLER ON THE [Junel4, 



and Blanchard (3). If we carefully, with the aid of a seeker and 

 pair of scissors, open up the ventral wall of this space, we shall find 

 that it tapers off posteriorly on the ventral side of the rectum and 

 appears to end at a small distance in front of the cloaca (varying in 

 different species). On the other hand, we find that it ends anteriorly 

 in front of the reproductive glands. It is in fact, like the corre- 

 sponding space in Birds, Crocodiles, and Tupinambis, an intestino- 

 genital cavity. 



As the right reproductive gland lies, in Snakes, in advance of the 

 left, this posterior peritoneal space extends forwards farther on the 

 right side than on the other. 



In the male we shall prohably have no difficulty in making out 

 the anterior limits of this space, just in front of the anteriorly 

 rounded testes. 



But in the female it may not be always easy to say exactly where 

 this space does end anteriorly. If we follow the oviduct of either 

 side forwards, we find the anterior end of its funnel continued as a 

 thread into a narrow, forwardly directed, funnel of peritoneum. On 

 the right side \_cf. (3) pp. 100, 101] this narrow peritoneal funnel or 

 tube runs forwards just externally to the portal and postcaval veins, 

 and is the remnant, as will be explained later, of the right half of the 

 peritoneal cavity in this region, which, down to a comparatively late 

 embryonic stage, persists as a narrow tube (tig. 3^, P") placing the 

 posterior peritoneal space now described in communication with 

 that in which the right lobe of the liver lies. Similarly with the 

 small funnel on the left side. We can frequently tell approximately 

 where these peritoneal tubes or funnels end, and this was especially 

 clear in a specimen of Heterodon d'orbignii. While sometimes it 

 is hard to say this, it is not very important to know the exact 

 point at which such tapering tubes end, especially as it is, in nearly 

 all cases, perfectly clear that the anterior peritoneal spaces into 

 which they might be expected to lead are closed behind '. The 

 wonder is not that where, as in the females, these forwardly directed 

 peritoneal funnels occur they should vary as to their extension 

 forwards, but that the original embryonic continuity of the peritoneal 

 cavity on either side is, so far as I can ascertain, never maintained in 

 the adult. 



Before leaving this hindmost division of the peritoneal cavity, 

 which, as stated, extends in the male (and except for insignificant 

 tubular processes in the female also) from the anterior border of the 

 reproductive organs to a point on the rectum usually not far from 

 the cloaca, it may be well to say a few words as to the viscera which 

 project into it. 



Ks stated in § II., the relations of the peritoneum to the alimen- 

 tary canal have been repeatedly noticed by writers on Snakes, from 

 Meckel {loc. cit.) to the present day {cf. for instance RoUeston, 



^ It is ouly rarely that the right half of the liver tapera off backwards 

 along the course of the posterior vena cava. When this is so, it may be some- 

 times difficult to say exactly where the tapering liver-sac ends. [Liophis 

 mere/nii, Vi2)era arictans, V. nasicornis, Crotalus durissus.] 



