324 



MARSUPIALIA, 

 Fig. 141. 



Uterine fcetus with chorion and foetal appendages, Macropus major. The foetus is magnified twice the natural size. 



(b, Jig. 141) was spread out, its figure ap- 

 peared to have been that of a cone, of which 

 the apex was the umbilical chord, and the 

 base the terminal vessel above-mentioned. 

 Three vessels could be distinguished diverging 

 from the umbilical chord and ramifying over it. 

 Two of these trunks contained coagulated 

 blood, and were the immediate continuations 

 of the terminal or marginal vessel : the third 

 was smaller, empty, and evidently the arterial 

 trunk. Besides the extremely numerous rami- 

 fications dispersed over this membrane, it dif- 

 fered from the chorion in being of a yellowish 

 tint. Theamnios (c, 141) was reflected from 

 the umbilical chord, and formed, as usual, the 

 immediate investment of the fcetus. 



The umbilical chord measured two lines in 

 length and one in diameter. It was found to 

 contain the three vessels above-mentioned, with 

 a small loop of intestine; and from the ex- 

 tremity of the latter a filamentary process was 

 continued to the vascular membrane. The 



margins of the umbilicus or abdominal open- 

 ing were very strong, offering much resistance 

 to their division. On tracing the contents of 

 the chord into the abdomen, the two larger 

 vessels with coagulated blood were found to 

 unite; the common trunk then passed back- 

 wards beneath the duodenum, and after being 

 joined by the mesenteric vein, went to the 

 under surface of the liver, where it penetrated 

 that viscus: this was consequently an omphalo- 

 mesenteric or vitelline vein. The artery was 

 a branch of the mesenteric. The membrane, 

 therefore, upon which they ramified, answered 

 to the vitellicle, i. e. the vascular and mu- 

 cous layers of the germinal membrane, which 

 spreads over the yolk in oviparous animals, 

 and which constitutes the umbilical vesicle of 

 the embryo of ordinary Mammalia. The fila- 

 mentary pedicle which connected this mem- 

 brane to the intestine was given off near the 

 end of the ileum, and not continued from the 

 ccecum, the rudiment of which was very evi- 



