238 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XX. 



In Pusa this year, dragonflies are extraordinarily abundant, and have the 

 appearance of a locust swarm when they hawk together in the still evenings ; 

 I have never seen anything approaching the number there are, and not in one 

 place only but all over the country-side. The abnormal rainfall (75 instead 

 of 45 inches) has perhaps enabled them to breed more than usual ; it is the 

 larger forms, not the Agrionids, which are abundant. There is also an 

 abundance of Culex fatigans, Steqomyia fasciata and Anopheles fuliginosus ; 

 whether the last really conveys the fever that is raging all round or not is 

 not known, but there is a very great abundance of this Anopheles, which is now 

 coming more into houses and which particularly shelters in thatched huts and 

 buildings ; the enormous abundance of dragonflies has not checked them nor 

 other mosquitoes, and considering the habits of dragonflies it is hardly likely 

 that they would kill mosquitoes. 



(e) — What is a species ? 



The Bulletin Scientifique de la France et la Belgique, fasc 3, contains a 

 long memoir by A. Delcourt, entitled " Recherches sur la Variabilite du 

 genre Notonecta " (Enquiry into the Variability of the genus Notonecta), 

 Commencing with a discussion of the described European species, the author 

 details researches into the genus Notonecta in Europe, founded on collecting 

 and interbreeding, his collecting alone covering 30,000 specimens. The enquiry 

 is directed into determining how far the genus Notonecta consists of distinct 

 species, i.e., how far the systematist's recorded species are species. He 

 reduces the six or more definitely described species into four " categories 

 valables de classification " which we may roughly describe as " distinct classifi- 

 able forms," with variable forms due to habitat. He suppresses one species, 

 creates a new definite one, and extends one to cover so-called species and varie- 

 ties separated owing to degrees of pigmentation. He concludes that a system- 

 matist, describing new species from a collection say, necessarily makes 

 mistakes because he takes account only of morphology and cannot take 

 account of differing habitat, etc.; that is, species as described may not be dis- 

 tinct, and what the real conclusion is amounts to this ; that there are no de- 

 finite species, that forms have been derived from each other and from common 

 ancestors, that there are intermediates between so-called species and no clear 

 limits between species can be founded on Morphological characters alone. 

 We give a free translation of what the author believes is the result of this 

 enquiry. " What matters, is not to give names to forms of organised beings, 

 but to distinguish that they are those which are perpetuated in the same state 

 till they vary and to ascertain what are their relations, as much to each other 

 as to their surroundings. Classification is a means, not an end, and, if taken 

 as expounded here, the conception of evolution follows, for, as Tower remarks, 

 new forms are the result of a rapid change in response fco external factors. 

 It does not require centuries to show them, it is enough to know how to see 

 them, but for that one must use approximate terms." 



