OPHIDIA. 375 



enters the abdomen with the vessels ; it then passes np towards the 

 stomach and enters the gut a little below the stomach. This duct 

 allows of the gradual passage of the yolk into the intestine during the 

 time of incubation \ 



Snakes [the non-venomous kinds, as the Coluber natrix], although they 

 lay eggs, as does the lizard, yet they are somewhat different ; for they 

 take the whole of the eggs into the oviducts at nearly one time, placed 

 at little distances from one another 2 , like the viper 3 , and then they are 

 laid to hatch out of the body as in the lizard. They must lay them at 

 very different times, for in one hatching I found the young of very 

 different sizes and formations. 



The eggs of snakes have no air in them as in birds ; probably as the 

 egg is softish and is capable of compression, there is no occasion for 

 such ; yet this is not a sufficient reason for the presence of air in the 

 bird's egg, viz. from their eggs not being compressible ; for it is increased 

 in the time of incubation, therefore it might be wholly accumulated at 

 that time. 



The egg of a snake has a strong coat or shell, which is slightly inter- 

 mixed with calcareous earth, under which is a pretty strong membrane 

 similar to the hen's egg 4 '. 



The two penises of the snake are formed on the outside as if erect 5 . 

 At what time they are drawn into the prepuce I do not know. This is 

 contrary to the quadruped. 



The parietes of the belly of the snake are formed open and unite 

 before they are ready to be hatched, and this union is so perfect that it 

 is not at first observable : even when not united, and when they may be 

 separated by the slightest touch, when they have run into one another, 

 it is impossible to conceive there was ever a separation. How high the 

 separation goes I do not know, but I suspect no higher than the basis 

 of the heart ; for, in the youngest I have examined, the whole cavity 

 containing the viscera was open, and it did not seem to have gone 

 higher and now united, for I could not separate the ring or transverse 

 scale above, which I could easily do in older ones, where union had 

 taken place at and below the heart. 



The union begins first at the upper part and goes on towards the 

 anus, where it finishes around the umbilical cord, leaving no space 

 there, as in the chicken, for the entrance of the yolk just before birth 

 or hatching. In this animal the yolk is consumed in the time of 



1 [Hunt. Preps. Phys. Series, Nos. 3318—3324.] 2 [lb. Nos. 3301—3303.] 



3 [lb. Nos. 3309, 3310, 3311: in the two latter specimens the embryo viper may 

 be seen in the ova within the oviduct.] 



* [lb. Nos. 3304—3308.] 5 [lb. Nos. 3321, 3322, 3324.] 



