AFFINITIES OF MARSUPIALIA. 89 



be replied, that the affinity of the marsupials to 

 the oviparous vertebrata is admitted by every 

 naturalist, being shown in the small size of the 

 1 jrain and consequent exposure of the cerebellum, 

 iC absence of the septum lucidum and corpus 

 dlosum in the brain, and various other traits. 

 Professor Agardh says — " The marsupials are 

 mammalia which approach very nearly to birds; 

 the monotremata, in particular, almost coincide 

 with them."* Professor RvTuer Jones, of King's 

 College, whose testimony on such a point will be 

 admitted by the reviewer, speaks of the marsupials 

 us " connecting links between the oviparous and 

 placental vertebrata." Striking traits of their affi- 

 nity' to birds are shown, he says, in the structure 

 of the ear and of the reproductive organs.f In 

 reality, the whole figure of the cursorial bird, the 

 small head upon the long neck, the extreme length 

 of the hinder limbs, and the imperfect development 

 of the fore extremities, as well as the tendency of 

 the feathers to a hair-like chiiracter, sp^^^ak irre- 

 sistibly for its approach to certain marsupials. The 

 omithorhynchus is as clearly an advance from the 

 natatorial bird towards the rodent form, the latter 



* AIImaQ "Wext Biologi — apud Charlesworth's Magazine, Juljt 

 1839. 

 t General View of the Stractare of the Animal Kingdom. 



