VIVIPAROUS ANIMALS, 401 



germination or evolution appears to take place in quadru- 

 peds according to two different plans. In the first, there 

 is no adhesion of the germ to the walls of the uterus, while, 

 in the second, placentation or adhesion takes place. 



In the Marsupial genera, which we have seen are fur- 

 nished with a complicated uterus, there is no trace, in the 

 young, after birth, of any umbilical cord ; at least Sir E. 

 HOME could not detect any in the foetus of the kangaroo 

 after exclusion *. He has given a representation of a sub- 

 stance found in an impregnated uterus -f-, which he con- 

 ceives to be a foetus, in an early stage of formation ; but 

 which does not bear the remotest resemblance to the sub- 

 ject. From the communications made to him by Mr CON- 

 SIDE x, it appears that the impregnated uterus is filled with 

 a gelatinous substance, of a bluish-white colour, in con- 

 sistence like half melted glue, and so extremely adhesive as 

 to be with difficulty washed off from the fingers. From 

 the observations of Mr BELL, which were likewise commu- 

 nicated to Sir E. HOME J, it appears that the double ute- 

 rus of the wombat is filled, in its impregnated state, with 

 the same kind of gelatinous substance which closes up the 

 ora tinea. " I made a longitudinal incision into the lar- 

 gest of the uteri, and found its coats lined with the same 

 jelly met with in its os tincae. Continuing the incision 

 through this jelly, and at the same time using gentle 

 pressure, there issued a quantity of a thin pellucid fluid, 

 accompanied by an embryo wrapped up in very fine mem- 

 branes, which contained some of the same transparent 

 fluid. The membranes did not appear to be at all connect- 

 ed by vessels either to the uterus or gelatinous matter. I 



Phil. Trans. 1795, p. 233. f Ibid - Table xx - Fi S- 2 



Phil. Trans. 1808, p. 309. 



VOL. I. C C 



