OCR Text |
Show 348 DR. J. MURIE ON THE [May 26, side or middle third of the cricoid cartilage, and being inserted into the outer arytenoidal facet. The fleshy digastric arytenoideus muscle (Af) is of considerable thickness, much expanded at the posterior face of the arytenoid cartilages, and narrow at their middle line of junction. 1 may record of the crico-thyroid and the posterior crico-arytenoid muscles that they each are broad, fleshy, of medium thickness, and respectively, along with a well-developed kerato-cricoideus which is present, cover the entire surface of the cricoid cartilage. Of the extrinsic laryngeal muscles 1 need say nothing. The osseous pieces composing the hyoidean arch correspond in number with those of Antelopes ; the bones are slender rather than otherwise. Relatively the stylo-hyal (S. h) is long, namely, 2*8 inches ; its proximal end has a considerable-sized dependent quadrate plate, and a broadish short upward styloid process, lengthened, however, by a tip of cartilage. The epihyals are ossified, and each 0*5 inch long. The cerato-hyals (C. h), with a long diameter of 0*7 inch, are slightly curvilinear and intermediate in stoutness between the preceding and the thyro-hyals. The basihyal (B. h) is narrow, notable by a prominent tuberous rostrum and partially cartilaginous body. The thyro-hyals are connected to the thyroid alae by a cartilaginous terminal rod; the length of their ossified part is equal to that of the cerato-hyal. 6. PULMONO-VASCULAR STRUCTURES. The trachea consists of 56 cartilaginous rings counted to the bifurcation, but at the high division of the bronchus 45. In the Sheep there are altogether some 50 in number. The left lung possesses three lobes, the lowermost, as usual, being the largest. The right lung is divided into five segments, the four upper and smaller ones being long, narrow, and widely separated at their roots. The uppermost one of these receives a separate bronchus at 2| inches above the ordinary bifurcation. The heart conforms to the type of ruminants generally. The inferior vena cava enters behind and to the left; the fossa ovalis is closed, and the eustachian valve large. The superior vena cava has a thickish circular muscular layer as it enters the auricle. The auricles are relatively of small size compared with the ventricles. The valves agree with those of the Sheep ; but there is a more than ordinary fibrous network crossing between the lower walls of the left ventricle. A firm cartilaginous body (the bone of the heart) 0*3 inch long, lies at the anterior base of the aorta, beneath the tricuspid valves. The heart has little fat on its surface. It is sliglitly elongated in form, and fully 4 inches in length from base to apex. The aorta, after sending off the small cardiac branches, is single for a distance of 1*3 inch, and then bifurcates, the left larger trunk forming the arch and descending aorta. The ductus arteriosus is situated 0*8 inch from the above division. The right trunk, the |