366 Mr. R. M'Lachlan on Odonatafrom 



this from typical 0. japonicum, Uhler. The only one of any 

 importance was that the triangle of the posterior wing appeared 

 to be constantly traversed by a nervule in internum and con- 

 stantly free from such nervule in japonicum. Having 

 examined more examples, the same rule appears to hold good, 

 and as such a character when constant is regarded as of 

 specific importance, I here quote internum as a species. In 

 some females of japonicum the middle lobe of the labium is 

 dusky. As before, it is difficult to define any differences in 

 the genitalia. 



0. internum occurs also in the Khasia Hills and in other 

 localities of the North Indian side of the Himalayas. 



Orthetrum melania, Selys. 



A series of examples from Siao-Lou and also from Moupin, 

 the latter showing a still further western extension of the 

 species. The male previously noticed from Ta-chien-lu was 

 highly adult and pulverulent; those now before me are 

 mostly immature, allowing a comparison as to colours and 

 markings with the Japanese types. No differences are appa- 

 rent in the colouring of the body ; it is, however, probable 

 that the dark space at the base of the wings often remains 

 yellowish (not dark brown) in continental examples. 



Crocothemis servilia, Drury. 



A series of males from Moupin are remarkable for the very 

 dark, almost brownish, base of the wings, the colour being 

 also sharply delimitated on the posterior wings ; the neura- 

 tion is dark and the apical margin is usually narrowly dusky. 

 I have similar examples from the coast of North China. 

 These examples induced me to go through, probably for the 

 sixth time, a series of about one hundred specimens of Croco- 

 themis. They were attacked primarily with the idea of finding 

 specific, or strongly racial, characters in the specimens above 

 referred to, and secondly to test the possibility of separating 

 C. servilia and C. erythrcea. Neuration and the genitalia of 

 the second segment were especially examined. 



It is easy to say that large examples from Hong Kong or 

 Japan are servilia, and that smaller ones from Europe, Africa, 

 India, &c. are erythrcea, and it is tolerably easy to isolate 

 examples intermediate as to size, such as those from Moupin 

 &c. ; but once again have I failed to find any certain struc- 

 tural characters. There are slight neural differences, but only 

 such as are either individual or correlated with size, and there 





