lIYIilUDS — UV CaOSSiNG T. ItlSTOKtATA WITH T. CKEPUSCULAKIA. lOii 



in cop., usually between 7 and 9 p.m., iu one or two instances as late 

 as 12 p.m. On the other hand, with the three pairs of $ T. crepuscu- 

 larid with «? '/'. bistortatn, tlie moths were never seen together, and 

 consequently I left them (sometimes a $ with a single 3 , in other 

 cases a J with two or three g s) together for several days, and 

 searched the pots for ova subserpicntly. With the {)airings between 

 ? s and 3 s of the same species the mollis were usually seen in copuln. 

 It seemed to me so doubtful that the ova laid by J s of T. nupnscniaria, 

 [jlaced with J s of T. bidortata woidd prove fertile, that I wrote to 

 Dr. Hiding on the subject, and he most kindly fjrwai'ded to me some 

 ova of a cross he had obtained l)etween a $ T. ab. delamerensis and a 

 3 T. bidortata. I kept the following batches of ova myself, and all 

 my subsequent notes refer to these, or crosses obtained from these 

 stocks : 



Ref. No. Paired. j Parent. i Parent. Hatched. 



(BNo. 1) Feb. 20th T. bixtortata T. bistortata April 3rd 



(C No. 1) Mar. 5th T. cj-e})it.^cularia T. crepu.^cularia 



(X No. 1) Feb. 20th T. ab. dclamereitxis T. bixtortata April 0th 



(X No. la) T. bisiortiita 'T. crejniticuldria April 8th-'Jth 



(X No. 2a) T. bi.^tortnta T. crepusvularia 



(X Dr. 1\.) 7'. bistortata T. ab. delaniereusis 



Ova. — I was, this season, able to com})are and measure the ova of 

 the two species, and found, as Dr. Riding and Mr. Tutt have already 

 pointed out, that the ova of the two species are quite distinct. Ova 

 laid by three diilereut Js of T. bidortata gave the size as— length 

 about -03 inches, width -02 inches. Ova of three dilfereut J s of V. 

 crepttscularia (these were more ovate iu shape) gave — length abt»ut 

 •025 inches, width -01 7o inches. The ova of Scotch T. bistortata 

 were of the same size as those from Clevedon stock. Mr. Prout, and 

 myself also, carefully examined the ova of both species, to see if the 

 position or sculptiu'ing of the micropylar rosette could be used in 

 dilfereutiating the species. We had no difficulty in distinguishing 

 the eggs of the two species frcmi each other, size being the best guide, 

 though difterences in colour and shape were also apparent. The sculp- 

 ttu'ing around the micropyle was, however, of no use as a distinguishing 

 mark ; it was present in the eggs of Ijoth sjiecies, and its position often 

 varied in eggs of the same species. In one egg of T. bistortata the 

 rosette was on the side instead of the end, and in others it was on the 

 shoulder of egg. 



Larvae of 1st crossks. — The larvte of the cross (No. 1) 3 T. ab. 

 ddamerensis x ? T. bistortata fed up very rapidly, and quite out- 

 stripped larvce of T. bistortata, which had emerged from the egg three 

 days earlier than they had. By May i)th, nearly all were in their last 

 stage, many were full-fed, and a few had alreatly gone down. Their 

 coloration was rather duller and darker than that of 7'. bistortata, and 

 they mostly took after the (larvte of) $ parent with regard to the /\ 

 mark, only a very small i)r()porti<m having it open at the apex, but 

 these few had the gaj) as widi' and distinct as in larvre of 7'. crepnscularia. 



llyltrid larvit! of the rever.se cross J T. bistortata x ? T. crqnis- 

 cnlaria or 7'. ab. ddamerensis fed up more rapidly than the larviu of 

 the parent species, but not quite so rajiidly as larvte of the tirst- 

 meiitioned cross. One In'ood of this cross, however, produced a large 

 jiroportion of laggards, which continued feeding long after the 

 advanced larvic of the brood had gone down. Most of these 



