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Show 688 ON THE FIN-SKELETON OF BATOID FISHES. [Dec. 2. in the forward and downward slope of its anterior border. Whereas in the Sharks the vertical diameter of this cartilage is greatest at its middle, or near its posterior extremity, in the Chimaeroids it is greatest at its anterior end ; and in some respects the anterior border of tbe Chimseroid metapterygium repeats, in its relationships to the propterygium, the conditions of the mesopterygium of the Selachii. In its realization of these characters, and in the simple constitution of its cartilaginous rays, the pectoral metapterygium of Squaloraja closely resembles that of the living Holocephali; and, on careful comparison of the two, I am convinced that, with respect to the skeleton of its paired fins, that fish is indubitably, and as Dr. Giinther at first suggested1, a Chimseroid. In talking this matter over with Dr. Traquair during the autumn of 1889, I was much rejoiced to find that he had independently arrived at the same conclusion on a study of the skull, which he asserts2 is "of the autostylic structure." It is to be hoped that he will give us, with as little delay as possible, fuller details of this important discovery. M y best thanks are due to m y friend Mr. Smith Woodward, for his courtesy in having allowed m e to examine his matchless specimen. 1 Geol. Mag. vol. ix. (p. 148). Curiously enough he altered his mind later, in doubtfully referring it (' Introduction to the Study of Fishes,' p. 335) to the Pristiophoridce. 2 Nicholson & Lydekker's Manual of Palasontology, vol. ii. p. 950 (1889). |