MAMMALIAN ORDERS. 



279 



be remarked that the unusual number — three and twenty pairs 



of ribs, forming a very long dorsal, with a short lumbar, region of 

 the spine in the Two-toed Sloth, recalls a lacertine structure. 

 The same tendency to an inferior type is shown by the abdominal 



157 



Skull of Anteater {Myrmecophaga). 



testes, the single cloacal outlet, the low cerebral developement in 

 all Bruta, by the bony scutes of the Armadillos and the horny 

 scales of the Pangolins, fig. 158; by the absence of medullary 

 canals in the long bones in the Sloths, and by the great tenacity 

 of life and long-enduring irritability of the muscular fibre, in both 

 the Sloths and Anteaters. 



The order Bruta is but scantily represented at the present 

 period. One genus, Manis or Pangolin, is common to Asia and 

 Africa; the Orycteropus is peculiar to South Africa; the rest of 

 the order, consisting of the genera Myrmecophaga, or true Ant- 

 eaters, Dasypus or Armadillos, and Bradyjms or Sloths, are con- 

 fined to South America. The earliest known fossil of this order 

 is of miocene ao-e. ^ 



[58 



Skeleton of Scaly Anteater (Manis). lxxiii\ 



In proceeding to consider the subdivisions of the Gyrencephala, 

 we seem at first to descend in the scale in meeting with a group 

 of animals in that subclass, having the shape and life of Fishes ; 

 but a high grade of mammalian organisation is masked beneath 

 this form. The Gyrencephala are primarily subdivided, accord- 



» CLi. t, V. pt. 1, p. 193. 



