WHITTLEIA RETIELLA. 34l 



reticulatis, corpore nigro lanugine albido vestito. Alarum latitude) 

 •375 unc. Corporis longitudo *135 unc," &c] 



Imago. — Anterior wings 9mm. -10mm. in expanse, whitish with fine 

 broken transverse fuscous lines and dark nervures, giving the wings 

 a reticulated appearance. Posterior wings similar to the forewings 

 but basal area without reticulations. 



Sexual dimorphism. — $ . The male is fully winged with well 

 developed antennas, legs, &c. The antennas have 15 joints with scaleless 

 pectinations, the anterior tibiae have no spur, the posterior tibiae very 

 dilated, the wings clothed with highly specialised narrow hair-like scales, 

 some slightly broader and with defined striae, principally along the costa. 

 The female is vermiform, 6mm. in length, l-8mm. in width, and with 

 proportionately much less hard dark chitin anteriorly than a species such 

 as Pachythelia villosella, but it has some dorsal plates on the abdo- 

 minal segments, and possesses, in fair development, the rods of the 

 ovipositing segment. The dark head-parts consist of a horseshoe-like^ 

 ring, with subsidiary parts that may represent various mouth-parts, 

 but altogether a very small amount. The thoracic segments have no 

 dark plates ; on the abdomen, apparently on segments 3, 4, 5, 6 abdo- 

 minal, there are transverse dark chitinous plates dorsally ; they are not 

 black, but smoky tinted ; each carries four pale round spots, 

 apparently the trapezoidals, nearly in a transverse line, but the outer 

 (i) a little anteriorly. There are two rods to the 12th, and two to 

 the 13th segment (following Dr. Wood's descriptions), i.e., the two 

 terminal segments ; the latter -33mm. in length, the former twice as 

 long, each simple except in its spreading out in the chitin of its seg- 

 ment of attachment, which is, however, uncoloured, except close to the" 

 attachment (Chapman). The living female is banded with yellow like 

 a larva of Euchelia jacobacac, but turns nearly black after death (Merrin.) 



Variation. -The reticulated pattern of the forewings of the male 

 is subject to much variation (rule, pi. iv, which is taken from Mr. 

 Whittle's unequalled series of this species). This variation occurs not 

 only in the intensity of colour of the lines, but also in their width and 

 direction, asymmetry being very frequent on the opposite wings of 

 the same specimen ; the tendency for the external line of the fore- 

 wings to end on the outer margin and not at or within the anal angle, 

 and also the tendency for the two median lines to form a transverse band, 

 are very evident in some examples, whilst in the hindwings some speci- 

 mens exhibit the dark fuscous markings as distinct lines rather than 

 reticulations. In one example in Dr. Chapman's possession, the 

 outer fuscous line is thrown quite on the margin, forming a con- 

 spicuous black marginal edge to all the wings. There is also consider- 

 able variation in the shape of the wings, some being quite elongated 

 when compared with the ordinary squarish form with rounded apex, 

 and the peculiar pointed apex of the pupal wings leaves one in doubt 

 whether this elongation of the imaginal wings is really due to some 

 slight crippling or a tendency to atavism. A peculiar specimen, in 

 which the hindwings show a tendency to divide symmetrically,- is to 

 be seen at the head of Mr. Whittle's series, and whilst some show a 

 tendency to suffusion, others exhibit a falling off in the usual quantity 

 of dark markings. A very good idea of the general range of variation 

 exhibited by the shape and markings of this species may be derived 

 from the plate (iv). 



