166 Mr. W. L. Distant on new Cicadidee. 



variations, as a necessary condition for the production of 

 divergent races and species, he has pointed out one process by 

 which segregation is produced in nature. This one process is 

 geographical or local separation under different environments. 

 It may be the result of migration or of geological and other 

 changes in the environment; but, in either case, there is the 

 preservation of different variations through diversity of natural 

 selection due to the difference in the environments, and the 

 independent propagation of the same variations due to their 

 geographical or local separation. We have in this process an 

 important cause of segregation resulting in divergent evolu- 

 tion ; but no one can maintain that this is the only cause 

 producing segregation and divergence, unless he ignores the 

 fact that, in some cases, the isolated portions of a species, while 

 exposed to the same environment, acquire divergent habits in 

 the use of the environment, producing diversity of natural 

 selection ; and that, in other cases, without exposure to diffe- 

 rent environments, the very process producing the isolation 

 brings together those of one kind, preventing them from cross- 

 ing with those of other kinds, as when individuals of a special 

 colour prefer to pair together. In the former cases indis- 

 criminate separation is transformed into segregation ; and in 

 the latter cases the isolation is segregative from the first, 

 while in both classes of cases the divergence is without expo- 

 sure to different environments. 



Osaka, Japan. 



XXI. — Description of a new Genus of Oriental Cicadidae. 

 By W. L. Distant. 



Talainga, gen. nov. 



<j> . Body somewhat elongate, the abdomen cylindrical. 

 Head with the front globose and prominent, including outer 

 margins of eyes about as broad as base of mesonotum ; ocelli 

 about twice as far apart from eyes as from each other. Pro- 

 notum with the lateral margins ampliated, deeply notched 

 about centre, and then more broadly ampliated at posterior 

 lateral margins. Anterior femora robustly spined. Tegmina 

 talc-like, semiopaque, the whole apical area with the vena- 

 tion reticulate and forming a mass of small cell-like areas ; in 

 some specimens the ulnar areas are also crossed by transverse 

 veins ; interior ulnar area about same width at apex as at 



