1S91.] ON TADPOLES OFTHK EUROPEAN BATKACHIANS. 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 iierpetologisl. 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 ohstetricans, so common in many 

 parts of the Continent, but so seldom met with in the daytime, be- 

 trays its existence, through its tadpole, all the year round, the 

 breeding-time lasting throughout spring and sumlner, 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, .\lthougli excellent contributions to their study 

 have quite recently beeuptiblished 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 my 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 my own, I have endeavoured, in the following 

 pages, to supjily the long-felt desideratum. 



My 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 im- 

 portant characters afforded by the microscopical structure of the 

 labial teetii, 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 (" Recherches sur la structure et le developpement 

 des dents et du bee cornes chez Alytes obstetricans,* Arch, de Biol, 

 ix. 1888, p. 55), Heron Royer and Van Banibeke (" Le Vestibule de 

 la bouche chez les tetards ties Batraciens anoures d'Europe," Arch, 

 de Biol. ix. 1889, p. 185), and E. Gutzeit ("Die Hornzahne der 

 Batrachierlarven," Zeitschr. wiss. Zool. xlix. 1889, p. 4.3). The 

 development of the larvge 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. 



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