OCR Text |
Show 1 MR. 3. H. STEEL ON INDIVIDUAL [Jan. 6, a small ossific centre. Our cases of variation show us that we must describe this as the inferior extremity of the ulna The value of this observation as illustrating the similarity of the forearm of the Ass to that of the O x 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). , Hind.-Os innominatum : form, size, and relations ot auricular facet of ilium vary. Fibula varies similarly to ulna in fore limb. Often extends to tarsus, occupying whole length of outer part of tibia. In other cases, and generally, consists superiorly of a small button-shaped appendage externally placed to upper part of tibia, tapering to a point inferiorly, from which a white fibrous band extends downwards, becoming continuous with the inferior extremity of the tibia, the external part of which is developed from a distinct ossific centre, the representative of the tarsal fibula of Ruminants. 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 hyoides presents between cerato- and stylo-hyal on each side a bony nodule representing the epihyals, which are well developed 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 portion 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 progression as the horse. Hence we often find these sacs distended with |