600 MR. G. A. BOULENGER ON THE [Nov. 17, 



Sc. Angers, (2) xv. 1885, p. 107) suggests as a method of ascer- 

 taining their disposition, in cases when specimens can be sacrificed, 

 to strip tlie skin and spread it out on the convex surface of the 

 bottom of a test-tube, chosen to suit the size of the tadpole ; the 

 transparent skin may then be easily studied. 



Gr. Born (Arch. f. mikr. Anat. xxvii. 1886, p. 207) recommends a 

 method of studying and handling the lavvos in their fresh condition, 

 by paralyzing them through immersion in a solution of tobacco, as 

 was proposed by Lataste for fixing the adult in copula. The little 

 creatures become insensible after a few minutes, and remain so for 

 about half an hour after being transferred to pure water ; they 

 recover perfectly if the immersion in the solution has not been too 

 prolonged. 



As stated above, the object of this paper is to supply comparative 

 descriptions of the external characters of the Tadpoles of Europe, 

 so as to facilitate the identification of the species. But in order to 

 enable the reader to acquaint himself with the rather extensive 

 special bibliography, I have introduced copious references to the 

 authors who have previously dealt with the subject. I have also 

 briefly indicated the habitat and breeding-season of each species. 



In addition to the extensive material collected by myself, I have 

 been able to study many specimens received from M. Heron Royer, 

 M. E. Bosca, Dr. J. de Bedriaga, Prof. Born, Prof. Liitken, Dr. W. 

 "Wolterstorff, Prof. Giglioli, Dr. L. Joubin, and Prof. Camerano, to 

 all of whom I beg to tender my sincere thanks. 



The tailless Batrachians are represented in Europe by 19 species, 

 belonging to 8 genera and 5 families : — 



I. RANID^. 



1. Rana, L., 1766. 



1. esculenta, L., 1766. 



2. arvalis, Nilss., 1842. 



3. temporaria, L., 1766. 



4. grceca, Blgr., 1891- 



5. i6mca, Blgr., 187?. 



6. latastii, Blgr., 1879. 



7. agilis, Tho.m., 1855. 



II. HYLIDiE. 



2. Hyla, Laur., 1768. 



8. arborea, L., 1 766. 



III. BUFONID^. 



3. BuFO, Laur., 1768. 



9. vulgaris, Laur., 1768. 



10. viridis, Laur., I76S. 



11. calamita, Laur., 176b. 



