Classification of the Mammalia. 53 



orbits have not an entire rim of bone. Besides these more gene- 

 ral characters by which the Lissencephala, in common with the 

 Lyencephala, resemble Birds and Reptiles, there are many other 

 remarkable indications of their affinity to the Oviparous Verte- 

 brata in particular orders or genera of the subclass. Such, e. g., 

 are the cloaca, convoluted trachea, supernumerary cervical verte- 

 brae and their floating ribs, in the 3-toed Sloth ; the irritability of 

 the muscular fibre, and persistence of contractile power in the 

 Sloths and some other Bruta ; the long, slender, beak-like eden- 

 tulous jaws and gizzard of the Anteaters ; the imbricated scales of 

 the equally edentulous Pangolins, which have both gizzard and 

 gastric glands like the proventricular ones in birds ; the derma[ 

 bony armour of the Armadillos like that of loricated Saurians 5 

 the quids of the Porcupine and Hedgehog; the proventriculus of 

 the Dormouse and Beaver ; the prevalence of disproportionate 

 development of the hind-limbs in the Rodentia ; coupled, in the 

 Jerboa, with confluence of the three chief metatarsals into one 

 bone, as in birds ; the keeled sternum and wings of the Bats; the 

 aptitude of the Cheiroptera, Irisectivora, 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 co-affinity with the 

 Lyencephala to the Oviparous air-breathing Vertebrata, 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 association, through 

 some single character, with better-brained orders, according to 

 Mammalogical systems which, at different times, have been pro- 

 posed by zoologists of deserved reputation. Such, e.g., as the as- 

 sociation of the long-clawed Bruta with the Ungulata, and of the 

 shorter-clawed Shrews, Moles and Hedgehogs, as well as the Bats, 

 with the Carnivora ; of the Sloths with the Quadrumana ; of the 

 Bats with the same high order ; and of the Insectivora and Ro- 

 dentia in immediate sequence after the Linnean ' Primates,' as in 

 the latest published ' System of Mammalogy,' from a distinguished 

 French author. 



The third leading modification of the Mammalian cerebrum is 

 such an increase in its relative size, that it extends over more or 

 less of the cerebellum ; and generally more or less over the olfac- 

 tory lobes. Save in very few exceptional cases of the smaller and 

 inferior forms of Quadrumana (fig. 3) the superficies is folded 

 into more or less numerous gyri or convolutions, — whence the 



