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Show 1891.] ON TADPOLES OF THK EUROPEAN BATRACHIANS. 593 7. A Synopsis of the Tadpoles of the European Batrachians. By G. A. BOULENGER. (Plates XLV.-XLVII.) [Eeceived October 28, 1891.] The knowledge of the larval forms of Tailless Batrachians is of no small importance to the exploring herpetologist. The presence or abundance of many a species which, from concealing or nocturnal habits, is likely to escape detection may be readily ascertained through the recognition of the tadpole. To mention a well-known example, the Midwife Toad, Alytes obstetricans, so common in many parts of the Continent, but so seldom met with in the daytime, betrays its existence, through its tadpole, all the year round, the breeding-time lasting throughout spring and summer, so that the tadpoles of the later broods pass the winter in that condition. The presence in a locality of any given Batrachian thus ascertained, it becomes comparatively easy, through searching under stones or in holes in the daytime, or by going about at night with a lantern, to secure specimens of the adult. Tadpoles are, as a rule, easily seen and easily caught, but the identification of the species is often a matter of difficulty. Although excellent contributions to their study have quite recently been published by Heron Royer and Van Bam-beke, and by J. de Bedriaga, the absence of a concise synoptic treatment of the subject, accompanied by figures of all the European species, must have deterred many collectors from devoting to the subject the attention it deserves. During several weeks' vacation spent this summer in Brittany, I availed myself of m y leisure for collecting and comparing large series of tadpoles of various species, and by incorporating the results of the researches of the above-named and other authors with m y own, I have endeavoured, in the following pages, to supply the long-felt desideratum. M y object being to facilitate the determination of species on the spot, I have left out of consideration all such characters as cannot be verified by the aid of an ordinary lens. For the important characters afforded by the microscopical structure of the labial teeth, I refer the reader to the recent works of F. E. Schulze (" Ueber das Epithel der Lippen, der Mund-, Rachen- und Kiemen-hohle erwachsener Larven von Pelobates fuscus," Abh. Akad. Berl. 1888), H. Keiffer (" Reeherches sur la structure et le developpement des dents et du bee comes chez Alytes obstetricans,* Arch, de Biol. ix. 1888, p. 55), Heron Royer and Van Bambeke (" Le Vestibule de la bouche chez les tetards des Batraciens anoures d'Europe," Arch. de Biol. ix. 1889, p. 185), and E. Gutzeit ("Die Hornzahne der Batrachierlarven," Zeitschr. wiss. Zool. xlix. 1889, p. 43). The development of the larvae is also left out of consideration; my descriptions apply merely to the fully-developed tadpole, in the condition generally known as the "third period" in the larval development, the period between the budding of the hind limbs and the bursting out of the fore limbs. * 40* |