Report of the Annual Meeting Volume 1842 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1842 Excerpt: ...and upwards. A symmetrical bone, resembling the episternum of the Ichthyosaurus, was associated with the preceding remains. It consists of a stem or middle, which gradually thickens to the upper end, where cross-pieces are given off at right angles to the stem, and support on each a pretty deep and wide groove indicating strongly the presence of clavicles, and thus pointing out another distinction from Crocodiles, in which clavicles are wanting. Most Batrachians possess these bones. The modifications of the jaws, and more especially those of the bony palate of the Labyrinttuxlon leptognathus, prove the fossil to have been essentially Batrachian, but with affinities to the higher Sauria, leading, in the form of the skull and the sculpturing of the cranial bones, to the Crocodilian group, in the collocation of the larger fangs at the anterior extremities of the jaws to the Plesiosaurus, and in one part of the dental structure, in the form of the episternum, and the biconcave vertebrae, to the Ichthyosaurus. Another marked peculiarity in this fossil is the anchylosis of the base of the teeth to distinct and shallow sockets, by which it is made to resemble the Sphyraena and certain other fishes. From the absence of any trace of excavation at the inner side of the base of the functional teeth, or of alveoli of reserve for the successional teeth, it may be concluded that the teeth were reproduced, as in the lower Batrachians and in many fishes, especially the higher Chondropterygii, which formed the Amphibia Nantes of Linnaeus, iu the soft mucous membrane which covered the alveolar margin, and that they subsequently became fixed to the bone by anchylosis, as in the Pike and Lophlus. This anatomical fact militates strongly against the idea that the Labyrinthodon i...