OCR Text |
Show 394 PROF. HUXLEY ON THE REPRESENTATIVES OF [May 27, lage (S.St). The inner surface of the posterior edge of the suprastapedial cartilage is thus closely connected with the posterior part of the parotic process of the skull, while its anterior end conies into contact with the quadrate bone, which is connected with the front part of the same process. Fig. 1. S.St Qa Side view of the right side of the hinder part of the skull of a young Crocodilus biporcatus. The squamosal, the postfrontal, and the tympanic membrane are removed, and the quadrate (Qu) is, in part, indicated only by an outline. E. 0. Exoccipital. Pc.c. Cartilaginous termination of the parotic process of the skull. E.St. Extrastapedial process of the stapes. S.St. Its suprastapedial process. Sth. The stylo-hyal cartilage supposed to be seen through the quadrate bone, a, b. Air-chambers of the quadrate. B.p. Pneumatic duct, leading from the posterior of these (a) to c, the air-chamber of the articulare (Art). Mck. Meckel's cartilage. In the natural position of the parts, and when the head is horizontal (fig. 1), the plane of the extrastapedial cartilage is also nearly horizontal. The long axis of the suprastapedial cartilage is inclined at an angle of 45° to that of the extrastapedial cartilage; and the posterior ends of the two cartilages approach one another very closely. In close proximity to both lies the upper and broader end of a small and short rod of cartilage (Sth) which tapers below to a free rounded extremity. It lies upon the upper and posterior face of the quadrate bone ; and its lower extremity terminates some distance above the upper end of the pneumatic duct (D.p), the fibrous wall of |