430 



METAZOAN PHYLA 



outer end of the tunnel opening under the water. The egg is not incu- 

 bated but it soon hatches and the young is fed from milk produced by- 

 milk glands. However, there are no teats, the milk being passed into 

 two grooves on the ventral side of the mother's body. In nursing, the 

 mother lies upon her back and the young animal laps the milk from the 

 milk grooves. The spiny anteater. Echidna, possesses a temporary 

 pouch in which the eggs are incubated. 



-Olfactory 

 bulb 



^ /Cerebrum 



Cerebellum 



Fig. 320. — Brain of European rabbit, Lepus cunicuhis Linnaeus, seen from the side. 

 {From a Ziegler model, after Wiedersheim.) The roots of the cranial nerves are marked by 

 roman numerals. 



443. Marsupials. — In the case of the Marsupiaha (mar su pi a' li a; 

 G., marsypion, pouch) the egg has a thin membrane and only a little 

 albumen. It is retained in the uterus, the young being nourished through 

 the embryonic membranes, which are in contact with the uterine wall. 

 Rarely a primitive allantoic placenta is developed. The young is born 

 in an exceedingly immature condition and makes its way or is transferred 

 by the mother to a brood pouch, or marsupium, on the ventral surface 

 of her abdomen. Here it attaches itself to a teat, remaining so attached 



