1891.] TADPOLKS 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 pos- 

 teriorly, 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 spottejd, 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 ~n 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, 1 1 1 millim. long, is recorded by Pfliiger 

 (Arch. Ges. Physiol, xxxi. 1883, p. 141). 



In addition to the admirable illustrations of Rosel (Hist. Ran. 

 pi. xiv., 1 758), 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 (Z. c. pi. xv. fig. 5). 



I am 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 Palsearctic region. 



The breeding-season falls between the middle of May and the 

 end of June, the transformation of the 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 (Verb, zool.-bot. 

 Ges. Wien, xxi. 1871, pp. 38, 1267), Kessler (Bull. Soc. Nat. Mosc. 

 1878, p. 207), and Kollmaun (Verb. nat. Ges. Basel, vii. 1883, 

 p. 387'). 



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 



^ Lataste remarks, however (C. E. Assoc. Frang. xii. 1883, p. 570), that Koll- 

 mann has mixed up larvae of Pelohates fuscus and Sana esculenta under the 

 latter name. His largest specimen (105 millim. long) is stated to belong to 

 Felobates. 



