JOURNAL OF VARIATION. 



No. 11. Vol. II. November 16th, 1891. 



THE GENUS ACRONYCTA AND ITS ALLIES. 



By Dr. T. A. CHAPMAN. 



{Continued from page 175.) 



CRONYCTA (Cuspidia) strigosa. — I have had infer- 

 tile eggs, larvae, pupae and imagines of this species 

 for several years, but had completely failed to get 

 fertile eggs until this year, w^hen Mr. Farren of 

 Cambridge sent me a moth which laid over two dozen eggs. 



In i8go, for example, I had a number of pupas and obtained 

 nine moths. Among these moths, sleeved over a growing 

 thorn bush, nine pairings were observed to take place, but in 

 no instance with a satisfactory result. I believe others have 

 been more successful, and am therefore unable to say wherein 

 my procedure was faulty. Alni sometimes pairs in the same 

 useless manner and did so in every instance in 1890, whether 

 I or the season was to blame in either or both instances I 

 cannot say. In previous years the same arrangements had 

 been very successful with alni. The ^g'g is the smallest of the 

 Acroiiyctas, being only "74 mm. in diameter and is transparent 

 and colourless; the structure is that of the other species of the 

 genus, the ribs about 41 in number. The inner e,g^ shrinks 

 away from the outer, leaving a clear margin, but, the inner e.gg 

 remaining colourless, this is not so self-evident as in the 

 coloured species. In eggs laid on glass the development of 

 the larva is easily observed. When ready to hatch, the larva 

 presents very little colour except the brown jaw tips, a faint 

 Indian ink in the head, and indications of brown round the 

 margin where the dark segments lie, can just be made out ; 

 the position of the larva in the egg-shell being identical 

 with that oi psi, tridens and all the other Acronyctas so far 

 as I have observed, viz., with the head under the vertex 



