150 The Zoologist — March, 1866. 



ancestor. He conceived that tbe whole phenomena, both of the formation or develop, 

 meut of the different species and the existence of the intermediate vaiielies, were 

 explicable on the broad principle that an insect, in disseminating itself over a wide 

 area, adjusts or accommodates itself to local conditions. 



Mr. Saunders remarked that the Heliconiae exhibited were all from the same 

 locality, and therefore presumably had been subjected to like conditions. 



Mr. Bates admitted thai many different varieties were found in one spot; but as 

 local variation was not the only form of variation, such collocated varieties might be 

 produced by causes similar to those which produced the remarkable diversity between 

 tbe offspring of some of our domestic animals. 



Dr. Alex. Wallace said that the course which the discussion had taken led him to 

 enquire whether Bombyx Ricini aud Bombyx Cynthia were distinct species ; the two 

 insects interbred, and the hybrids were fertile and bred on for generatiims, not only 

 amongst themselves, but with either of the parent forms. And yet B. Ricini was from 

 Bengal and fed on Ricinus communis; B. Cynthia from China and fed on Ailautbus 

 glandulosa ; they differed in the egg, in the colour of the larvae, in the shape of tbe 

 cocoon, in the quality of the silk, in the imago, and in their habits. 



B. Ricini produced six or seven generations in the year, and was too fertile for this 

 country, since it could not be prevented from hatching in winter when no food for the 

 larvje was obtainable; whilst B. Cynthia, though last year it had produced four 

 generations in France, in an ordinary season produced only t»vo, and perhaps a single 

 generation would be the rule in this climate. 



Mr. J. J. Weir enquired on which plant the hybrids fed ? Dr. Wallace replied, on 

 both or either indifferently. 



Mr. F. Smith said that the remarks he had made at a previous Meeting, (see 

 'Proceedings,' 1865, p. 130), as to the tapping noise alleged to be made by " death- 

 watches," had induced Mr. Henry Doubleday to send him an account which shewed 

 that his (Mr. Smith's) doubt was, as to Anobium at all events, unfounded. Mr. 

 Doubleday, under date of Epping, 3l.st Dec. 18(i5, wrote as follows: — 



" I cannot speak positively about the Alropos, but I am strongly inclined to believe 

 that it is the insect which produces the continuous faint ticking sound so frequently 

 heard in the spring. It seems almost impossible that such a delicate little creature 

 should be able to produce any sound whatever, but T have always found it in places 

 from which the ticking sound appeared to proceed. I have often thought it very 

 wonderful that the pied woodpecker can, by striking the branch of a tree with its beak, 

 produce a sound which may be heard for half a mile ; we could not produce a similar 

 sound by striking the tree with a stick or anything else. I can speak positively with 

 regard to the Anobium, and I assure _>ou that this little beetle produces the loud 

 ticking sound, by raising itself upon its legs as high as it can, and then striking the 

 head and under part of the thorax against the substance upon which it is standing, 

 generally about five or six times in rapid succession ; and it always chooses a 

 substance which produces the most sound. It is evidently a call-note from one 

 individual to another, as you very rarely hear one rap without its being immediately 

 answered by another. I have repeatedly kept one in a card pill-box, and if I imitated 

 the sound, by tapping anything with a pointed pencil or something of that kind, the 

 Anobium would instantly answer me. This insect is common in our bouse, but it is 

 not very easy to obtain them, as, when you have found out by their rapping where they 



