936 



SCIENCE. 



[N. S. Vol. VIII. No. 209. 



the species, and these, as a whole, are de- 

 tailed more fully and with more discrimi- 

 nation than in any other work. Especially 

 noteworthy are the descriptions of the 

 courtship and oviposition of the species. 

 The ' amplexation,' or mode of approach of 

 the males on the females, is characteristic, 

 and in main features is common to the 

 members of a genus, so far at least as the 

 European species are concerned. So gener- 

 ally in conformity with structural features 

 has it been regarded that the principal 

 modifications have been used to differen- 

 tiate and diagnose certain groups. Atten- 

 tion was first called to the subject by A. 

 Thomas in 1854, and two groups^ were 

 named by Bruch, in 1863, Plagioglena and 

 Orthogiena, and by A. de L'Isle, in 1877, 

 Alamplexes and Inguinamplexes . But the 

 want of correlation between such characters 

 and structural ones is now evident. Mr. 

 Boulenger (p. 2) well remarks: " How 

 exaggerated the importance attached to 

 this correlation, which, besides, holds 

 good only for the European forms, is 

 now apparent to all." Nevertheless, within 



For example, Mr. Heron-Royer (Bull- 

 Soc. Zool. France, 1890, 205) recognized 

 7 categories of amplexation — pectoral, ax- 

 illarjf, supra-axillary, inguinal, axillo-in- 



Amplexation of ' Pelodytes pundahis^ 



certain limits, the species of a genus agree 

 in their mode of amplexation; only a. 

 too strict taxonomy cannot be applied. 



Amplexation of ' Bufo vulgaris^ 



guinal, lumbo-pubic, and lumbar. Ifow, Mr. 

 Heron-Eoyer recognized five European spe- 

 cies of Hyla, which are considered by Mr. 

 Boulenger to be varieties or variations of 

 the single species Hyla arborea, and yet two 

 of the nominal species are referred to one 

 category (axillary) and three to another 

 (supra-axillary). One of the European 

 toads {Bufo viridis) has a pectoral amplexa- 

 tion, two (-B. vulgaris and B. calamita') an 

 axillary, and the common American species 

 (J5. mudcus or lentiginosus) , a supra-axillary 

 habit. In fact, such differences may be 

 simple expressions of the relative size of 

 the male and female and must vary as do 

 the sexes. But there is a sharp contrast 

 between amplexation round the waist and 



