178 BRITISH LEPIDOPTEBA. 



of the cilia, (2) the length of the antennae, (3) the cervical tuft on the 

 middle of the prothorax, (4) the colour of the middle pair of tibiae, 

 (5) the neuration. 



With regard to the colour of the cilia, Heinemann asserts that on 

 this character the imagines may be divided into two great sections : 

 (1) The base of the cilia of the anterior wings clothed with broad 

 scales, which are pale at their bases and dark at their apices, so that 

 the cilia appear to be more or less pale with dark spots. These spots 

 generally arrange themselves so as to form several dark lines intersect- 

 ing the cilia entirely or partially, especially at the anal angle ; the 

 outer line is always the most distinctly and decidedly expressed, and 

 often it is the only one in which 'the spots unite to form a distinct 

 line. In some few species, e.g., X. salicis, X. floslactella, X. i-imineti- 

 cola, this line is not generally distinct, but the dark ends of the scales 

 project irregularly in the cilia ; but in all cases the latter, beyond such 

 a line or beyond the dark scales, decidedly and abruptly defined, are 

 paler, generally whitish. (2) Although scales project from the base 

 of the cilia, they are narrow, very little paler at the base than at the 

 apex, and, therefore, do not form so sharp and conspicuous a line as 

 in most of the species in the preceding section ; and, although, in 

 these, the tips of the cilia are paler, sometimes even whitish, the 

 colour only becomes gradually lighter, and certainly more from the 

 pale lustre of the tips of the cilia, whilst the latter in certain directions 

 are always distinctly grey. This divisional line in the cilia is termed by 

 Heinemann " the cilial line." On this character Herrich-Schiif lei- 

 separated X. turicella from A", basalella (tittjrella}, X. Kalicin from X. 

 floslactella, and X. arcuatella from X.fayi. 



As to the characters furnished by the length of the antenna?, 

 it is necessary to premise that usually the antenna? are longer in the 

 male than in the female, and therefore it is necessary to compare 

 males with males and females with females. Heinemann says that 

 "in a great number of species the antenna of the males reach above 

 two-thirds- or even three-fourths of the length of the anterior wings, 

 in which case the antennae of the females have rather more than half 

 the length of the wings ; in other species the antenna of the males 

 hardly reach beyorfd the middle of the costa, and the antenna? of the 

 females are considerably less than half as long as the wings. Some 

 few species stand midway between these sections." 



Of the cervical tuft, Heinemann writes : " Sometimes this is white, 

 and then forms, with the eye-caps, when the insect is sitting with its 

 antennas set back, a distinct white collar ; in .the red and yellow- 

 headed species the cervical tuft is often of the same colour as the 

 frontal tuft, but paler, and frequently it is quite concolorous with 

 the thorax." 



According to the same observer the middle tibiaa are generally 

 markedly paler than the posterior tibiae. Often they are quite white, 

 whereas in other species they are nearly as dark as the posterior 

 tibiae, <?.//., A'. ]>l(t;/icol<'lla is readily separated from its nearest allies 

 by its dark middle tibiae. But since the colouring of the tibia? varies 

 considerably with the direction of the light falling upon them, they 

 rarely afford, except in a few striking instances, a certain character. 



Herrich-Schaffer noticed that there were two forms of neuration 

 in the Nepticulids, one more complicated, the other simpler ; whilst 



