OCR Text |
Show 1891.] TADPOLES OF THE EUROPEAN BATRACHIANS. 605 form two series, extending from the end of the snout to the upper borders of the eyes, passing between the nostrils ; a pair of dorsal lines on each side of the back, close together in front, diverging posteriorly, are usually distinguishable ; these lines in the advanced tadpole coalesce to form the dorso-lateral fold of the perfect animal. Olive or greyish olive above, speckled with brown ; sides with silvery or pale golden spots; belly white; throat pinkish, with mother-of- pearl-coloured spots; tail pale greyish, closely spotted, dotted, or vermiculated with grey or blackish ; the muscular portion of the tail yellowish, often with three blackish stripes on its basal third. With advancing age, when the hind limbs are approaching to their full development, the back assumes a more decidedly greenish colour, and the pale green vertebral stripe, if it is to exist, makes its appearance. The largest tadpoles of the typical form which I collected this summer in Brittany measure 77 millim.: body 23, width of body 18 ; tail 64, depth of tail 20. Tadpoles of the var. ridibunda, sent from Prague by Hr. V. Fritsch, measure up to 90 millim. A specimen from the latter localitv, 111 millim. long, is recorded by Pfluger (Arch. Ges. Physiol, xxxi. 1883, p. 141). In addition to the admirable illustrations of Rosel (Hist. Ran. pi. xiv., 1758), this tadpole has been figured by Lataste (Actes Soc. Linn. Bord. xxx. 1876, pi. ix. figs. 4-6) and by Lessona (Atti Ace. Lincei, 3, i. 1877, pi. i. figs. 1, 4, 5), and the mouth by Heron Royer and Van Bambeke (I. c. pi. xv. fig. 5). I a m not aware of any differences by which to distinguish in the larval state the various races I have lately endeavoured to diagnose (Proc. Zool. Soc. 1891, p. 374). With the exception of the extreme north, the Edible Frog inhabits the whole of the Palaearctic region. The breeding-season falls between the middle of M a y and the end of June, the transformation of tbe larvae taking place normally from the middle of August to the end of September. Hibernating larvae are, however, not of very unfrequent occurrence. I have more than once found in Belgium full-grown larvae so early in the year that they must have passed the winter. Well authenticated cases of hibernation have been recorded by Kolazy (Verh. zool.-bot. Ges. Wien, xxi. 1871, pp. 38, 1267), Kessler (Bull. Soc. Nat. Mosc. 1878, p. 207), and Kollmann (Verh. nat. Ges. Basel, vii. 1883, p. 387x). 2. RANA ARVALIS, Nilss. (Plate XLV. fig. 2.) Although this species is closely allied to R. temporaria, it approaches in some respects R. esculenta, the spermatozoa, for instance, agreeing very closely with those of the latter species (cf Leydig, An. Batr. Deutsch. Faun. p. 137, pi. v., 1877). The tadpole likewise is 1 Lataste remarks, however (C. R. Assoc. Franc, xii. 1883, p. 570), that Kollmann has mixed up larvae of Pelobates fuscus and Bana esculenta under the latter name. His largest specimen (105 millim. long) is stated to belong to Pelobates. |