( Ixvii ) 



possessed by Campsogene and I'rotaml>iili/x. Here tlic corresponding spines are 

 slightly thinner than the more distal ones, but very little longer, the most 

 basal ones being even shorter than these. The comb occurs again in the 

 Sjiliiiiyifliir cem/Dtoj/Zwrar, especially in the lower forms ; bnt the bristles never 

 attain the length they have in Acherontiinae, resembling always more ordinary 

 spines and becoming gradually shorter (PI. LXIV. p. 'x). It will be noticed 

 in the figure quoted that the third row of spines does not reach the base of 

 the segment. 



The hindlarsHs is generally longer tiian the midtarsus, bnt agrees with it 

 in appearance. The comb, however, is less strongly developed, and is not part 

 of the fourth but of the third row of spines, which is very strange, and, like 

 all strange things in morjAology, very interesting. The combs of mid- and 

 hindtarsus serve doubtless both the same purpose — we think, of keeping the 

 abdominal fringe of the wing in order, and, in the S <S. perhaps also to brush 

 the tuft of the abdominal scent-organ. As the hindtarsus is in a di&'erent position 

 to the body and wings, the position of the comb has become altered, or, rather, 

 another row of spines has developed into a comb. As the four ventral rows 

 of spines of the three tarsi are homologous organs, and as the comb of the 

 hindtarsus is homologous to the third row of spines of the midtarsus, we see 

 clearly that the appearance of the comb ou the hindtarsus is not due to an 

 inner factor of development causing the comb of the midtarsus, developed for 

 some purpose, to be repeated ou the hindtarsus. It must have been an 

 extraneous factor — i.e. adaptation — which was the cause of the development 

 of the same kind of orgau from different sources. 



The second and foufth rows of sjiiues of the first segment of the hindtarsus, 

 or only the fourth, do not reach the base. 



The fifth segment of all tarsi bears some stout an<l pale sensory hairs at the 

 end on each side close to the apical sjiine, forming often a brush. There are two 

 long bristles dorsally close to the edge, curving ventrad (PI. LXIV. f 9 — 15). 

 In a few instances the number of bristles is larger in some individuals, there 

 being occasionally as many as four or five ; but this is quite an exception. The 

 pair of bristles is normal not only for the Spkingidae, but also for a number 

 of other families. In Butterflies and .Skippers we find from four to ten bristles ; 

 in Spliinifiihie, Noctuidae, Notodontidae, Lasioeampidrie, etc., there are two ; 

 while the bristles are absent or vestigial in I'l/ralidae, Zygaenidae, Aegeriidae., 

 llepialidue, Tineidae, etc. The character is of taxonomic value. Thyrididae 

 with two bristles and I'yralidae without them can thus readily be distinguished. 

 In Satuniildae and Urainidae the two large bristles are generally accompanied 

 by several smaller ones. 



The daw-segment is one of the most interesting organs of insects, on account 

 of its very numerous modifications. It does not seem to us to have been made 

 use of in systematic works on Jleteroccrn. The elements of which it is composed 

 are the claw [nnycliiidn), the I'also claw {paroni/rhiiiin), the i)a(l {pulcillu.<<), and 

 the empodium. 



