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Show 666 MR. G. A. BOULENGER ON T H E [June 16, 3. A Description of the German River-Frog {Rana esculenta, var. ridibunda, Pallas). By Or. A. BOULENGER, F.Z.S. [Eeceived June 4, 1885.] (Plate XL.) When I received a year ago a large number of Rana esculenta from Berlin, I was so struck by the differences they presented that I had no hesitation in regarding them as of two distinct races or subspecies, and I bestowed upon the one which was new to me, and to which attention had previously been called by Prof. Pfiiiger \ the name of R. fortis. As I had not then sufficient material to establish a comparison with all the forms which had already been named by-various authors, this seemed to me the best course, m y object being to draw immediate attention to the remarkable fact of two distinct closely allied forms occurring in the same locality, reserving for a future occasion an investigation into the chaotic synonymy. I have since constantly been amassing material; and I think I may flatter myself on having now before me the finest and largest series of specimens of R. esculenta with accurate localities which has ever been _ brought together. Unfortunately, the more specimens I examine, the more difficult the subject appears; and I should not think of attempting at present a general revision of the races of this widely distributed species. It is evident that under the name Rana esculenta a number of forms are thrown together, the extremes of which are as distinct as many we are accustomed to regard as valid species; but as they are linked together by numerous insensible gradations, it is best to regard them as subspecies. The great number of specimens, both alive and in spirits, which have lately passed through my bands, have more and more strengthened my belief in the constancy of the characters upon which I have based the distinction of R. fortis and R. esculenta ; but they have also convinced me that the name R. fortis should be cancelled in favour of the name R. ridibunda, Pallas. M y object at present being merely to give a detailed account of the recently discovered German Frog, I will leave aside all further material in order to avoid confusion, and all that is said of R. esculenta for comparison applies only to German specimens. The following description is based on the examination of about 130 specimens of R. ridibunda, of which six are from Prague, the rest from Berlin. RANA ESCULENTA, var. RIDIBUNDA. Rana ridibunda, Pallas, Reise, i. p. 458 (1771). Rana cachinnans, Pallas, Zoogr. Ross.-As. iii. p! 7, pi. i. fi<*s. 1 2 (1831); Eichwald, Faun. Casp.-Cauc. p. 126, pi. xxx. (1841). 1 Arch. f. Physiol, xxix. 1882, p. 67. |
