198 Prof. Westwood on the adult larvcs 



Pig. 3. The head-case of the full-grown larva, with part of the succeeding 

 segment seen from above, but looking rather obliquely forwards, 

 shewing the transverse lip (e); the two projecting auricles (h)y 

 two of the circular discs (^a); and one of the pairs of spaces 

 behind the head (/I). 



Fig. 4. Shews the head-case of the larva seen sideways, shewing the more 

 convex surface (g), which lies upon the dorsal surface of the 

 abdominal segment of the Andrena. 



Figs. 5, 6 and 7. Shew the head-case of the larva of the Stylojjs seen in 

 different positions with the auricles and other oi-gans lettered 

 alike throughout the different figures. 



Fig. 8. Mandible of Hylechtlirus rubi. 



Fig. 9. Exti'emity of palpus of ditto, with the terminal part of the last 

 joint folded back. 



Fig. 10. Antenna of ditto, with the terminal portion of the first branched 

 joint broken off. 



Reference to Lettering. 



a — e 



Head-parts. 



/ 1, 2, 3 . . 



. . Podal analogues 



9 ■■ 



Dorsal region. 



X and y 



Alary analogues 



z 



. . Spiracle. 



If we regard the upper series of circlets in the seg- 

 ments behind the head of the larva of Stylops seen in 

 fig. 2 (fl,f2,f'S), as representing the legs of the imago 

 in a very rudimentary state, and the two polished spaces 

 below {x and ?/) as corresponding with the elytra and 

 wings, it will be evident that the immature imago seen 

 in fig. 1, with the legs downwards, must have turned 

 itself half over so as to bring its dorsum opposite to 

 where the leg-rudiments had previously been, since the 

 projecting auricles and other organs of the head retain 

 the same relative position in both figs. 1 and 2. 



Thus the larva represented in fig. 2 must have 

 protruded its head through the connecting tegument of 

 the abdominal segments of the Andrena with its dorsum 

 downwards ; and hence we are fin^ther led to consider 

 that the more convex portion of the head of the larva of 

 Stylops (fig. 4, g) is in reality the dorsal region, and 

 that the male Stylops imago would have emerged from 

 the puparium with the legs upwards and back downwards 

 had it not turned within at some intervening period. 

 I remain, yours very truly, 



J. O. Westwood. 



Postscript. — Figs. 11 and 12 have been added, in 

 order to shcAv the arrangement of the thoracic segments 

 and their organs as seen in the exuvia (or larval skin) of 



