34 



valence of disproportionate development of the hind limbs in 

 the Rodentia, coupled, in the Jerboa, with confluence of the 

 three chief metatarsals into oiie bone, as in birds ; the keeled 

 sternum and wings of the Bats ; the aptitude of the Cheirop- 

 tera, Insectivora, and certain Rodentia to fall, like Keptiles, 

 into a state of true torpidity, associated with a corresponding 

 faculty of the heart to circulate carbonized or black blood : 

 these, and the like indications of coaffinity with the LYEN- 

 CEPHALA to the Oviparous air-breathing Yertebrata, have 

 mainly prevailed with me against an acquiescence in the 

 elevation of different groups of the LISSENCEPHALA to a higher 

 place in the Mammalian series, and in their respective associa- 

 tion, through some single character, with better-brained orders, 

 according to Mammalogical systems which, at different times, 

 have been proposed by zoologists of deserved reputation. 

 Such, e. g., as the association of the long-clawed Bruta with 

 the Ungulata 1 , and of the shorter-clawed Shrews, Moles and' 

 Hedgehogs, as well as the Bats, with the Carnivora 2 ; of the 

 Sloths with the Quadrumana 3 ; of the Bats with the same 

 high order 4 ; and of the Insectivora and Rodentia in immediate 

 sequence after the Linnean 'Primates,' as in the latest pub- 

 lished < System of Mammalogy,' from a distinguished French 

 author 5 . 



So far as their ordinal affinities are known, the most 

 ancient Mammals, the fossil remains of which have been found 

 in secondary strata, are either ly- or liss-encephalous, and belong 

 either to the Marsupialia or the Insectivora. (Appendix A). 



In the GYRENCEPHALA WQ look in vain for those marks of 

 affinity to the oviparous vertebrate animals which have been in- 

 stanced in the preceding subclasses ; although, it is true, that 

 when we proceed to consider the subdivisions of the GYREN- 



1 Macleay, Linn. Trans. Vol. xvi. (1833) ; Gray, Dr. J. E., Mammalia in 

 the British Museum, i2mo, 1843, p. xii. 



2 Cuvier, R^gne Animal, 1829, p. 'no. 



3 De Blainville, Osteographie, 4to, Fasc. i. p. 47 (1839). 



4 Linnaeus, Systema Natures, Ed. 12, Tom. I. p. 26. 



5 Prof. Gervais, Zoologie et PaUontologie Franpais, 4to, 1852, p. 194. 



