24 THE ENTOMOLOGIST. 



has been given. This must have entailed great labour upon the 

 author, but its value can scarcely be over-estimated. 



Mr. Distant appears to have encountered the usual difficulty 

 in defining the limits of a species, but his remarks on this head 

 are very sound, and he has an excellent method of generalising 

 the differences between closely-allied races or species ; for instance, 

 at page 28 he points out that between Euploea diocletianus of 

 Northern India, E. rhadamanthus of Malacca, and E. lowii of 

 Borneo, the principal difference is that of a gradually increasing 

 melanism, which is least in the North Indian and greatest in the 

 Bornean form. Such truly philosophic observations, with which 

 the book abounds, render the reading of it a delight. 



The author makes very short work of mere variation, and 

 suppresses Mr. Moore's name of Danais (Salatura) intermedia for 

 the variety of D. genuta with a more or less white ground to 

 the under wings ; on the other hand he gives full prominence to 

 the name conferred on a well-marked boreal race ; for instance, 

 Danais melanippus is a Javan species, not found in the Malay 

 Peninsula, where its place is taken by Danais melanippus var. 

 hegisippus, as Mr. Distant terms it. This differs from the type 

 in having a white ground to the under wings, but this difference 

 is constant, and not occasional as in Danais intermedia, Moore. 

 This last name is not well chosen, although it is desirable to 

 have some name to express the difference between the type and a 

 well-marked variety. Mr. Distant has, therefore, in a similar 

 case, adopted the name of Danais chrysippus var. alcippoides for 

 the variety of that species, with white in the centre of the under 

 wings, and has figured it, Plate XL., No. 13 ; still this variety is 

 occasional only. The variety of the dark African form of 

 D. chrysippus, alcippus, is in many parts of that continent 

 the common, if not the only form ; at Accra and the Cameroons, 

 for instance. It is singular that in several species, and in widely 

 different parts of the world, there should be a tendency in the red 

 Danaine butterflies to have a variety with white under wings ; 

 indeed in the case of Danais (Salatura) edmondi, from the 

 Philippines, the white colour extends to the upper wings, which 

 have but a faint trace of rufous. Can this whiteness be due to 

 reversion to the colour of an ancestor the common parent of 

 the species now placed in the genera Limnas and Salatura ? 



In conclusion it may be said that the work is a credit to the 

 author, the chromo-lithographer, and the printer. — ^J. J. W. 



