4 MR. J. H. STEEL ON INDIVIDUAL [Jan. 6, 



a small ossific centre. Our cases of variation show us that we 

 must describe this as the inferior cvtremitij of the ulna. The 

 value of this observation as illustrating the similarity of the forearm 

 of the Ass to that of the Ox is evident. 



Carpus : os trapezium v. pisiforme generally present, but some- 

 times absent. 



Metacarpus and Phalanges : major variations do not come under 

 our notice (in the Ass). 



Hi7id. — Os innominatum : form, size, and relations of auricular 

 facet of ilium vary. 



Fibula varies similarly to ulna in fore Hmb. Often extends to 

 tarsus, occupying whole length of outer part of tibia. In other cases, 

 and generally, consists superiorly of a small button-shaped appen- 

 dage externally placed to upper part of tibia, tapering to a point 

 inferiorly, from which a white fibrous band extends downwards, be- 

 coming continuous with the inferior extremity of the tibia, the exter- 

 nal part of which is developed from a distinct ossific centre, the re- 

 presentative of the tarsal fibula of Eumiuants. 



Tibia and astragalus : synovial fossettes vary in development. 



Smaller tarsal bones very frequently united by ankylosis into 

 a single mass, without any external indication of disease. This is 

 the condition known to veterinary surgeons as "occult spavin." We 

 are not yet prepared to attribute to it any morphological importance. 



Cuneiforme parvum composed of one or of two portions. 



Splanchnoskeleton. 



Ossification or calcification of the posterior portion of the sclerotic 

 occurs in old Asses. 



Os htjoiJes presents between cerato- and stylo-hyal on each 

 side a bony nodule representing the epihyals, which are well deve- 

 loped in the Ox. 



An OS cordis has been observed in the Ass ; it is always present in 

 the Ox. 



Myology. 



Head. — We generally observe muscular fibres which run from the 

 antero-external angle of orbicularis palpebrans beneath zygomaticus 

 to the outer surface of buccinator. These represent lachrymo- 

 labialis of the Ox, and are seldom seen in the Horse. They are 

 deficient in some Asses. 



Retractor labii superioris sometimes has a supplementary por- 

 tion which runs from the common point of origin of the muscle to 

 the tendon of the nasalis longus labii superioris, which it draws 

 downwards, and also to spread out by some of its fibres over the 

 superior part of the "false nostril." 



The "false nostril," the peculiar nasal pouch of Equidse, undergoes 

 considerable variation at its extremity, sometimes presenting a slight 

 tendency to bifidity of its cul-de-sac. In the Ass it is seldom used ; 

 for the animals are never driven to such extremes of rapid progres- 

 sion as the horse. Hence we often find these sacs distended with 



