OCR Text |
Show 1894.] TELEOSTEAN MORPHOLOGY. 419 Anatomical Features. The Alimentary Viscera.-The abdominal cavity is much elongated, extending back rather beyond the first third of the anal fin, and terminating in a narrow process, the apex of which, in a specimen 47g inches long, is 32 inches from the snout. The alimentary tract, as compared with that of the Common Ling, exhibits features of some interest. The cardiac portion of the stomach, which, as in the Ling, is prolonged backwards beyond the small bulbous pyloric portion, occupies the whole length of the visceral cavity except the narrow canal-like process already referred to. It is extremely thin-walled and flaccid, and thus in marked contrast to the firm muscular stomach of the Ling. The pyloric caeca are numerous, as in the Ling, but somewhat larger. The delicacy of the walls may be said to be characteristic of the whole of the alimentary canal in the Birkelange. It reaches its maximum in that part of the intestine which is beyond the origin of the pyloric caeca. The walls are here so thin as to be ruptured at the slightest attempt to lift the gut, and, in one specimen, were found to have been ruptured before the visceral cavity was opened. The intestine is very much shorter, as well as more delicate, than in the Ling, as will be readily understood by a glance at Plate X X I X . figs. 3 and 4l. It also appears to be subject to variation in its arrangement, the condition in two examples, both females, being shown in figs. 3 and 3 a. The liver is very much larger than in the Ling. It consists of a single ventral lobe, in which the coalescence of lateral elements appears to be indicated by the presence of deep sulci. It is somewhat expanded anteriorly, while the posterior process appears to pass indifferently either to the right or left of the rectum. In the Gadidae a greater development of the liver seems to be frequently characteristic of the more abysmal members of a genus. The mesenteries are as stout as in the Ling. The Air-bladder.-This is a simple fusiform structure, occupying the roof of the abdominal cavity from the anterior extremity to the origin of the ureter. It differs from that of the Ling chiefly in that its anterior cornua, which lie external to the attachments of the pharyngeal muscles to the vertebral column, possess no lumen, and that its dorsal wall is somewhat more spongy and less definite than that of the commoner species. The rete mirabile, a single structure, 4 inches long by 1 inch broad in a specimen 47g inches long, occupies the usual position, and is, if anything, a little smaller than in the Ling. The Kidneys.-These terminate posteriorly in a small expanded process, from which the ureter passes obliquely forward to the region of tbe vent. The posterior process is much larger in the Ling, and blocks the narrow end of the visceral cavity. On the 1 Smitt (op. cit. p. 524), in a very brief account of the visceral anatomy, notes that no part of the intestine, in a male 65 cm. long, extended beyond the anus. |