6474 Tendency of Species to form Varieties. 



Bittacus (of a species very common here) carrying a large fly along by one of its hind 

 tarsi : the fly had evidently been abstracted from a spider's web, as it was wrapped in a 

 webby shroud. 



" It is worthy of remark how few species of Lepidopterous larva I can find ; 

 I imagine the greater number of them must feed at night, or high up on the 

 trees. 



" December 5. — I am going to morrow to some large woods near at hand to endea- 

 vour to obtain some wondrous butterflies I have been informed of ; they have, according 

 to my informant (an observant old farmer), ' hard wings ' which 4 snap ' when they fly ; 

 they keep entirely within the forests, and are found sucking the sap from the Polygalae 

 that grow there: I thought of Cicada?, and suggested them to my informant, but he 

 knew the latter well, and insisted that those he meant were butterflies ; and that there 

 were several kinds, all large, and one with two tails on each hind wing. The only one 

 I have in my descriptions as possessing two tails on each wing is Charaxes Xiphaeus ; 

 it is probably that species. 



" December 13. — I have been out to-day in the woods, from 8 a m. to 3 p.m., but 

 although I visited the express woods mentioned by my informant, I saw nothing of 

 the ' snap-wing ' butterflies he described; indeed, though a splendid hot day, I saw 

 very little in the insect way in the forest itself, though near it I captured a large and 

 beautiful Trochilium, which must, I think, be quite new to Science, and some fine 

 specimens of Danais Chrysippus." 



Mr. White observed that no doubt the snapping sound alluded to was similar to 

 that produced by the Agerona?. 



Mr Waterhouse read a paper entitled " Notes on the British species of Hetero- 

 cerus.'' 



The President announced that the Council had resolved that all Members and 

 Subscribers, whether residents in London or otherwise, shall in future be entitled to 

 receive the Transactions of the Society gratuitously. — E. S. 



The Tendency of Species to form Varieties. — Of the papers upon this subject which 

 have appeared in the 1 Zoologist' (Zool. 6293 — 6308), those of Mr. Darwin seem to 

 extend the operation of his theory into a period resembling geological epochs, which 

 carries us at once into the region of conjecture, — a "barren ground," upon the bound- 

 less wastes of which I have no inclination to wander. If, however, Mr. Darwin's 

 hypothesis supposes perceptible changes, and embraces the time present, it is sub- 

 mitted that the following observations may be not unworthy of attention in reference 

 to his reasoning, and I would suggest for consideration whether the views (concluding 

 the meaning of both writers to be essentially the same) propounded in the papers 

 alluded to above are not founded upon the imaginary probable, rather than obtained 

 by induction from ascertained facts, which last process I do not hesitate to pronounce 

 the only solid and satisfactory basis of a new opinion. As (the italics are his own) 

 Mr. Wallace writes (Zool. 6305), of "progression and continual divergence, deduced 

 from the general laws which regulate the existence of animals in a state of nature," 

 he argues (if I understand him correctly) that the production of varieties is of con- 

 stant occurrence; and, according to his position (Zool. 6304), that "the variety would 



