68 CAUDAL VERTEBRA. [CHAP. 



ankylosed vertebrae ; the first two, or true sacrals, are broad . 

 and behind these the sacrum suddenly contracts. 



In the Lemurina the number of united vertebrae varies 

 from 2 to 5. 



In the CARNIVORA, there are generally few true sacral 

 vertebrae, only 2 in the Puma, Proteles, and Hyena. 2 or 3 in 

 the Tiger ; in the Bears and Seals as many as 4 or 5 may 

 be united by bone in old animals. In the Dog there are 

 usually 3 ankylosed vertebras. 



In most UXGULATA and RODF.NTIA the sacrum consists of 

 one broad vertebra joining the ilia, and a series of narrow 

 ones, varying in number with age, gradually diminishing in 

 width, ankylosed to it behind. 



In the Beaver among Rodents, most Chiroptera, the Cape 

 Anteater (Oryderopus) among Edentates, and the Wombat; 

 among Marsupials, the sacrum consists of numerous anky- 

 losed vertebrae, with widely-expanded transverse processes, 

 which are longer in the hindermost vertebrae, and nearly 

 meet the ischia. 



In most other EDENTATA, as the Sloths, Anteaters, 

 Armadillos, and in Pteropus among Chiroptera, this modi- 

 fication is carried further, and the transverse processes of the 

 hinder pseudo-sacral vertebrae form a complete bony union 

 with the ischia, converting into a foramen what is usually 

 the sacro-sciatic notch. In some of the Armadillos as many 

 as 10 vertebrae are thus firmly fused together, and with the 

 innominate bones. 



In MARSUPIALIA usually but one vertebra supports the 

 iliac bones, though another is commonly ankylosed with it. 



In the MONOTREMATA, the Ornithorhynchus has 2 

 ankylosed sacral vertebrae, and the Echidna 3 or 4. 



The CETACEA having no iliac bones, have no part of the 

 vertebral column specially modified into a sacrum : but in 



