1906.] 



ANATOMY OF THE OPHIDIA. 



35 



foetal membranes were in much the same condition as in the case 

 of the newly-born jEunectes notceus described above. The " navel " 

 (text-fig. 8) is, however, in this Viper much smaller than in the 

 Anaconda. The actual patch of skin uncovered by scales only 

 occupied the extent of two of the ventral scales, which were here 

 divided into two. On either side a small number of the ventral 

 scales were divided in the middle line, but there was no interval 

 between the two halves of each scale. Moreover, only two scales 

 anterior to the navel and four behind it were thus divided. The 

 conditions, therefore, are distinctly different from those obtaining 

 in Eunectes. Furthermore, the position of the navel differs. In 

 Bitis only 10-14 scales intervened between the navel and the 

 cloacal orifice : the actual distance was 14 mm., the whole snake 

 measuring some 9| inches *. The embryonic veins were apparent, 



Text-fiff. 8. 



Eegion of umbilicus in nevvlj'-born Bitisjiasicornis. 

 77. Umbilical sac. 



as in Eunectes. The umbilical vein can easily be traced from the 

 " navel " to the vena cava inferior, which it enters towards the 

 anterior extremity of the liver. As in Eunectes, this vein has no 

 relation whatsoever to the anterior abdominal vein that I could 

 discover. It has, however, an obvious connection with the epi- 

 gastric vein, which leads me to introduce the matter here, not as 

 a contribution to the anatomy of the Yipers, but as explanatory of 

 the anatomical facts vv^hich I have just referred to in the Python f. 

 Close to the union of the umbilical vein with the vena cava a branch 

 ascends from the epigastric to join the umbilical. This seems to 

 me to be a fact supporting the inference which I have put forward 



* In Vipera be7-us also the navel is close to the cloacal aperture 

 t Above, p. 29. 



3* 



