12 MAMMALIA. 



toral muscle. In the Elephant and Horse, the whole sternum is 

 very much compressed latterly. The ensiform process is frequently 

 short and pointed, sometimes, however, it is very long, and expanded 

 behind into a thin cartilaginous disc, as in Myrmecophaga, Dasypus, 

 Manis, and some Rodentia ; in some Edentata it extends nearly to 

 the pelvis. In the Ant-eaters the anomaly is exhibited of the costal 

 cartilages passing between two portions of the sternum so as to meet 

 and become united from opposite sides. In the Monotremata the 

 manubrium and body of the sternum are united by a capsular articu- 

 lation. Many of the pieces of the body of the sternum frequently 

 coalesce, as in the Horse and Elephant. 



The Scapular Arch presents very many differences. A Scapula is 

 generally present ; it is very broad even in the Cetacea, and has for 

 the most part a spine, though that may be but slightly developed, as 

 well as a coracoid process. The latter, which is wanting in Phoca, 

 is very long, on the contrary, in the Cheiroptera. The scapula 

 is remarkably long and narrow in the Mole, and its form is simi- 

 lar though of smaller proportion in the other Insectivora, as Sorex. 

 It is small also in the Ruminantia, throughout which order the 

 acromion is wanting along with the clavicles. In many Rodentia 

 a hook-shaped process arises from the spine posteriorly, as in Le- 

 pus. The broadest and most peculiar shaped scapula is seen in the 

 Edentata. In the Cheiroptera its form approximates the human, 

 frequently more so than that of the Apes, where it is, as in the 

 Chimpanzee, longer, and the neck, as in the Orang-utang, usually 

 very broad. 



The Clavicle is completely wanting in the Cetacea, Ruminantia, 

 Solidungula, Pachydermata, and some of the Rodentia and Carniv- 

 ora, as Phoca, Ursus, Nasua ; it is found very small, flat, and simply 

 imbedded in the flesh in the Dog and Hyena, but larger in the 

 Badger, Otter, and Cat, where it is represented by a sickle-shaped 

 rib-like bone. It is present in the Marsupiata and Insectivora. 

 Among the latter the Mole has a very remarkably formed, short, 

 quadrangular clavicle provided with a joint for articulation with the 

 humerus. In some Rodentia it is small, connected merely with the 

 sternum, and does not extend as far as the scapula. In the Chei- 

 roptera it is very large and strongly arched. In the "Quadrumana it 

 agrees for the most part in form with that of Man, though it is pro- 

 portionately thicker and stronger, as in the Orangs. 



The Humerus is in general a rounded and long bony tube, but 

 exhibits most remarkable differences. In swimming and fossorial 



