SCIENTIFIC NOTES. 151 



obtained the following evidence of the existence of a red form of 

 ttnidentaria : — I. Mr. Nelson M. Richardson has twice bred broods 

 containing both red and black specimens from dark red or " purple-red " 

 $ 's. II. Mr. W. H. B. Fletcher has bred a similar mixed brood from 

 a i^iack ? . III. I'he late Mr. C. S. Bouttell of Catford bred about 

 two dozen specimens from a red 2 , half coming out black, half red or 

 intermediate. IV. Mr. A. U. Battley, of Stamford Hill, has bred a 

 small brood of black specimens from a red J . Thanks to the courtesy 

 of these gentlemen, and of Mr. J. A. Clark (who is in possession of 

 some of Mr. Bouttell's brood), which courtesy I take this opportunity 

 of publicly acknowledging, I have been able to examine several of 

 these specimens. V. I have myself twice bred mixed broods, black 

 and dull red, once from a red ? , once from one so worn that its colour 

 was indistinguishable. VI. It should perhaps be added that Captain 

 R. B. Robertson bred last season from a red and from a black $ , the 

 pup^e being unfortunately mixed ; but he has kindly shown me some 

 of the red specimens that resulted, and they are of the same form as 

 Mr. Fletcher's red unideutaria. I may add that some are in possession 

 of Mr. Sydney Webb, who agrees that "they must be unideutaria'^ 

 Of the existence of a black form of ferrugata I can get no authentic 

 information, though I have bred two which are darker and duller than 

 some red tmidentaria. 



It need hardly be said, however, that the mere existence of a red var. 

 of uiiidentaria no more justifies our %\x)}fXvi^ ferrugata as a species, than, 

 for instance, would the existence of a ^^;«'^^^-like form of Apamea 

 gemina (Tutt, Brit. NoctucB, vol. i., p. 87) justify us sinking the former 

 species as a var. of the latter ! Assuming the ordinary view to be 

 correct as to what constitutes a species, the evidence wanted is — Do 

 the two forms pair in a state of nature ? If not, are they distinguishable 

 in any stage ? Several entomologists who have bred both forms have 

 pronounced the larvae indistinguishable ; but Mr. Sydney Webb has 

 been more discriminating, and has succeeded in differentiating them. 

 He writes : — " The caterpillars are quite different in colour when first 

 hatched, but after the first moult, almost indistinguishable one from 

 the other until nearly full fed, when a dark dash appears upon 

 the anal segment, at the side of the larvte ; and this mark bears 

 much resemblance to that upon the imagines of Notodonta dictceoides 

 and N. dictcea, being a dash in the one case, an elongated triangle in 

 the other," If these differences are found always to hold, they will 

 presumably be sufficient to mark the two as specifically distinct. As 

 for the imago, several points of distinction between the red unideutaria 

 and ferrugata have been suggested, though the variability of both 

 species renders it difficult to say which can be relied on in all cases. 



Mr. N. M. Richardson says of red unideutaria that '* the red is 

 generally rather darker than typical ferrugata and often of a purplish 

 tint ; " but his own personal opinion is that the two are forms of one 

 species, connected by intermediates. He has shown me one typical 

 ferrugata bred among some unideutaria from a dark red 5 ; this 

 specimen went round in one of the " Record Exchange Club " boxes, 

 and Mr. Sydney Webb suggested that it must have been accidentally 

 introduced among the brood ; unless this was the case it seems to show 

 that ferrugata is only a specialized form of unideutaria, and can be 



