254 



Mr. (i. A. iMiuk'iiocr on tlie lutrcs aud 



first ^raile, \v(> may place tlie var. chinousis in the second, 

 the var. ndVumda in tlie tliiivl, and tlie vais. saharica 

 .ind ItttSDmr. in tlie t"()intli. L x'kii:^- at things from a 

 }>racti('al standpoint, we must rcj^anl the var. saharica as 

 l)Ut a .slight nvulilicalion, a gcooiapliical laco distinguishable 

 from its nearest neighbour but im|)ossible to detine if 

 specimens from tlie whole range of distribution of the 

 var. ridihundii are taken into consiileration. The typical form 

 i.s completely connected with the var. ridtbunda, and where 

 the two co-e.\ist in :i locality, nnnectant individuals may be 

 regarded as the result of crossing, such as undonbtetlly 

 must take place ; but this explanation fails when we have 

 to deal with specimens from France, S.E. Europe, ai.d 

 Asia, where individuals of uncertain identification like- 

 wise occur, although the discrimination of tlie two forms is 

 in most cases quite easy. It is no longer so when we come 

 to the typical torm compared with the var. lessonce, and in 

 this case the naming of certain s[)ecimens is perfectly 

 arbitrary, us those wlio have had to deal with a consideiul)le 

 material from places where the two forms co-exist fully 

 admit*; _yet, the extreme, what some would call tlie " pure 

 le-ssonce" such as it occurred in the Cambridge fens and is 

 still found in a very few loealiiies in Norfolic, is well entitled 

 to varietal rank, its structural characters being fixed and so 

 considerable in degree when coin|)ared with the typical fornj 

 that it would undoubtedly be looked upon by many as a 

 Sj)ecies were we not acquainted with the annectant examples 

 from the Continent. These extreme specimens of the var. 

 lessonce represent the terminus of an uninterrupted series 

 starting from the var. ridibunda and passing through what 

 is called the typical form. 



Another terminus form, in which the princi|)al charactei's 

 of the var. lessome are repeated, is the var. dnnensis, which 

 in all probability is also derived from the var. ridibunda, 

 but the connecting-links of which have disappeared or are 

 still unknown. If we appeal to the existence of a hiatus 

 between forms as a sole criterion for deciding on what 

 is a species, then R. chinensis is entitled to stand as such ; 

 however, considering the many points of agreement, and 

 preferring to keep an eye on resemblances rather than 

 on differences, the raidc of variety or subspecies appears to 

 me the more apj)ropriate for this forn), as it did to Lataste 

 many years ago f. Owing to the state of things in the 



* Cf. Wolterstoi-flf, Schr. Nat. Ges. Danzig, (2) xi. 1904, p. 40. 

 t liull. Soc. Zool. France, 1880, p. 01. " Cette foniie, que qiielques 

 auteurs regardtut couniie iir.e espoce distincte, d'autrc:? coiuuje uiie 



