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Show 664 MR. G. A. BOULENGER ON PTERYGOID [DeC. 2, 2. On the Presence of Pterygoid Teeth in a Tailless Batra-chiau {Pelobates eultripes), with Remarks on the Localization of Teeth on the Palate in Batrachians and Reptiles. By G. A. BOULENGER. [Eeceived November 1, 1890.] On recently examining some disarticulated bones of Batrachians, which I prepared in 1877, and which I had not looked at since, I was very much surprised to find a few small teeth on the left pterygoid bone (the right one had been lost) and on the parasphenoid in a skull of Pelobates eultripes. My attention once drawn to this point, which is of considerable importance from the fact that pterygoid teeth have not yet been recorded in any living Batrachian, I examined the various skulls of Pelobates in the British Museum, and also removed the mucous membrane from the palate of several specimens in spirit, with the result that, although I have failed to detect any teeth on the pterygoids or parasphenoid of Pelobates fuscus, I have succeeded in finding pterygoid teeth in two other specimens of P. eultripes, one from Nantes, the other from the south of France. I will designate the former specimen as a, the latter as 6, and the imperfect skull (from Bordeaux), mentioned above, as c. In all three these teeth are small, grain-like, resembling the same in various Stegocephala ; the mucous membrane of the palate has to be removed to ascertain their presence ; they are evidently in a rudimentary condition. In specimen a there are about ten teeth on tbe parasphenoid, at the base of the longitudinal branch of the ^-shaped bone, and two pterygoid teeth close together on the left side. Specimen b has no teeth on the parasphenoid nor on the left pterygoid, but shows a group of eight distinct teeth on the right pterygoid. In specimen c, as in a, there are about ten teeth on the parasphenoid, aud a series of four on the left pterygoid (the right being lost). Our knowledge of the localization of the teeth on the various bones of the palate in Batrachians and Reptiles has so much increased of latel that it appears to m e useful, on this occasion, to review and tabulate the data available at present in recent aud fossil forms. Whilst in not a few fishes all the bones of the palate are toothed, it is only among the lowly Stegocephala that we meet, higher up in the scale, with such a disposition. As evolution proceeds in both the Batrachian and Reptilian phyla;, we find the palatal dentition more and more localized and reduced. Thus, in the Urodeles or tailed Batrachians, we have frequent examples of a toothed parasphenoid, no form, however, showing teeth on the pterygoids, but all agreeing iu having them on the vomers and palatines2. In the 1 A table, very incomplete even at the time it was published, of the dentition of recent Batrachians is given by O. Hertwig in his admirable memoir " Ueber das Zahnsystem der Amphibien," Arch. mikr. Anat. xi. Suppl. (1874). 2 In the Proleidce the palatines are not yet separated from the pterygoids in most Urodeles they are fused with the vomers. |