Skeleton of Common Rat. 9 



scapho-lunar, as they are also in Carnivora and Chiropteva, a bone, 

 the OS centrale, exists between it and the os trapezium, or trapezoides, 

 and OS mag-num in the second row of carpals, which is not repre- 

 sented by a distinct bone in the human carpus, nor in those of 

 Ungulata, Cetacea, Chiroptera, Edentata, Marsupialia, and Mono- 

 tremata, but only in those of Rodentia, Insectivora, and Simiadae, 

 exclusively of the Chimpanzees. As in all mammals, though in no 

 reptile nor amphibian, a single bone, the os unciforme, supports 

 the two outer metacarpals. In this enumeration the ulnar sesa- 

 moid bone, or ' os pisiforme,^ is not reckoned as a carpal bone, nor 

 any bone of similar function in connection with the tendons on the 

 volar side of the hand. 



In Rodentia we find tv\''o more bones in the tarsus than we do in 

 the human subject, owing to the division of the os scaphoides, and 

 to the presence of an accessory bone on the inner side of the inner 

 OS cuneiforme. 



For the general characteristics of Mammalian vertebrae, see Pro- 

 fessor Owen, Descriptive Catalogue of the Osteological Series 

 of the Royal College of Surgeons, vol. i. pp. 7, 8. 

 For the nomenclature of the several elements of a vertebra, ibid, p. xli v. 

 For the Osteology of the Rodentia, see Cuvier^s Ossemens Fossiles, 

 2nd ed,, 1823, vol. v. pt. i. pp. 4, 14, 44; and GiebeFs Beitrage 

 zur Osteologie der Nagethiere, 1859. 

 For the Carpxis and Tarsus and Shoulder-girdle, see Gegenbaur's 

 Untersuchungen zur Vergleichenden Anatomic, Hft. i. ii. 

 1864, 1865. Carpus and Tarsus, Hft. i. pp. 42 seqq., ^^, 

 109 — III, et passim. Schultelgiirtel, Hft. ii. p. 21. 

 For the 'Canalis Temporalis,' see Otto, Nova Acta, xiii. pt. i. p. 27, 



and Kolliker's Entwickelungsgeschichte, p. 422. 

 For the means whereby the vertebral centra are articulated in the 

 different classes of vertebrata, see Ratlike, Entwickelungs- 

 geschichte der Wirbelthiere, mit einem Vorwort von A. KoUiker, 

 1861, p. 130. 

 For the characters of the order Rodentia, see Waterhouse, Natural 



History of the Mammalia, vol. ii. pp. i — 9. 

 For the Osteology of the Muridae, see Osteological Catalogue, 

 Royal College of Surgeons, vol. ii. Preparations 2223 — 2245. 



