. Cassell's natural history. Animals; Animal behavior. TUE AFKICAN MCD-FlVH. ID about tlie same length, and all short; they are bent downward in the tail, so as to form an inferior arch like ;al arch, after the manner which is usual in,fishes. The skull is penetrated by the cranial end of the notochord, though it there becomes ossified. The skull is divided into distinct cranial segments, each formed of bones. The lower jaw consists of two pieces—a dentary bone in front and the articular bone beliiud. The jaws are armed with two slender conical teeth on the pre-maxillary bones, an
. Cassell's natural history. Animals; Animal behavior. TUE AFKICAN MCD-FlVH. ID about tlie same length, and all short; they are bent downward in the tail, so as to form an inferior arch like ;al arch, after the manner which is usual in,fishes. The skull is penetrated by the cranial end of the notochord, though it there becomes ossified. The skull is divided into distinct cranial segments, each formed of bones. The lower jaw consists of two pieces—a dentary bone in front and the articular bone beliiud. The jaws are armed with two slender conical teeth on the pre-maxillary bones, and with a strong dental plate on both the lower and uppin' sides of the mouth. These teeth are marked with ridges, and were originally compared by Sir K. Owen to the teeth of Ceratodus—then .supposed to be extinct—and the teeth of Chiman-a. Tliere are no teeth on the bones of the palate. The intestine is straight and short; it terminates in a spiral valve formed of sLx gyrations. The. vent does not open in the middle line of the body. There is no trace of a pancreas or .spleen, but the dark-brown liver has a gall-bladder in a notch of its left margin. The bile is conveyed by a duct into the intestine. The brain closely resembles that of Amphibians. This genus is tingjiished ' by possessing six branchial arches with five intervening clefts, and has three small branchial appendages above the small gill-opening. The air-bladder has a longitudinal partition, so as to divide it into two elongated sacs, which are supplied with venous blood from a pulmonary artery. Each of these sacs is divided into cells, which are more numerous in tin' fore-part of the bladder than in the hinder part. It is by means of these incipient lungs tluit ivspiiation is carriea on during the dry months, when the animals live out of water. Air is intiuihucd directly into the- air-bladder, and the opening of the duct from it into the cesophagus is kept distended by a cartilage like a rudimentary lar
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecta, booksubjectanimals
