1906.] 



ANATOBIY OF THE OPHIDIA. 



13 



The whole lengths of the two specimens which I have examined 

 wei-eas follows : — Specimen A, 21 inches ; Specimen B, 19;i inches. 

 The distance between umbilicus and vent was naturally greater 

 in the larger specimen, and the umbilicus itself larger. 



In the above given measurements I regard as the navel not merely 

 the actual aperture in the skin through which the yolk-plug* pro- 

 trudes, but the whole area which is devoid of scaling. The yolk- 

 plug in the interior of the body extends from the gall-bladder 

 anteriorly to the end of the kidneys posteriorly, and lies above the 

 fat-body. It is a dense solid plug. Meckel's diverticulum arises 

 from it just behind the umbilicus, and enters the small intestine 

 about an inch behind the pancreas. 



The umbilicus itself is so exactly median in position (text-fig. 2) 

 that it has divided the epigastric vein, which, instead of lying to 

 one side or the other, forms a loop surrounding it. As elsewhere 

 this vein is single, the position of the umbilicus could, I imagine, 

 be detected in a more fully adult snake by this splitting and 

 rejoining of the epigastric vein. 



Text-fie-. 2. 



V.S. 



■ UJTlb 



Region of umbilicus in newly-born Anaconda {JSunectes notceiis). 



umh. Umbilical area; Y.8. Ventral scales anterior to umbilicus, which are still 

 divided into two ; V.S' . Similar ventral scales behind the umbilicus. 



In the two newly-born Anacondas the area of the navel em- 

 braced nine of the ventral scales, which are split into halves, each 

 half lying on either side of the soft median area. Anteriorly and 

 posteriorly two scales showed a median groove, indicating, it is to 



* Messrs. Mole & Urich (P. Z. S. 1894, p. 505) mention the existence of " traces 

 of the umbilical cord " in newly-born Etmectes murinus. 



