1800.] ■ 211 



Mr. Briggs has misquoted and apparently misuuderstood my 

 remark that the differences pointed out " become intensified or modified 

 as the opposite extremes of variation are approached." This must 

 necessarily be the case wJien series of any two allied species, v;hich vary 

 much in colour and marJ^inqs, are compared together. 



I consider that the characters of the second line and the pale line 

 which follows it afford the " peculiar characteristics " of cratcBgella, 

 which are never shown in mercurella, and that an examination of those 

 lines will always reveal the identity of any specimen. Of the dis- 

 tinctions mentioned on pp. 99 — 101, my belief is that the special 

 points referred to in 6 and 7 invariahly hold good, that no specimens 

 are forthcoming to disprove those in 3 and 5, and that no two series 

 of the two species in question will disprove the remainder. I can only 

 repeat that " in every instance I believe that several of the points will 

 be found to hold good," namely, 6, 7, and one or more of the rest, 

 which are not quite invariable, though they hold good as a rule. 



It has been suggested to me, and apparently with good reason, 

 that cratcegeUa is a more finely -scaled species than the other, and that 

 this may account in a measure for its peculiarly neat appearance which 

 the eye readily grasps ; the point seems worthy of careful attention, 

 and further investigation. 



The present difference between Mr. Briggs and myself seems to 

 lie m the fact that he has seen specimens " which might with equal 

 confidence be referred to either species ;" and finds it " impossible to 

 distinguish the intermediates ;" whilst I, on the other hand, have in 

 vain searched everywhere, both in nature and in cabinets, for speci- 

 mens which, to my eye, are truly "intermediate," or equally referable 

 to either species. It seems to me that although, as is of course 

 natural, the two species vary in the same directions (though not, in so 

 far as is known, to the same extent), the parallel forms of each are all 

 quite distinguishable throughoxd. Let us hope that before long a 

 critical comparison of the larvae, and of the anal appendages of per- 

 fectly fresh specimens, may reveal the truth, and set the matter at 

 rest ; but it seems clear that for the present, at any rate, Mr. Briggs 

 and I must "agree to differ" on the subject. 



Erratum. — Page 100, line 7 from top, /or " almost invariably," 

 read " generally." 



The Rectory, Corfe Castle : 

 May, 1890. 



[No useful purpose can be served by continuing this controversy 

 at present. If any entomologist can bring forward facts concerning 

 life-history, or special points of structure, we hope he will make them 

 known. — Eds.] 



