Hetcrogyiiis imradoxa. 727 



no hairs, and are something very different from the true 

 tubercles, yet when only slightly magnified they look just 

 like them and are somewhat mystifying. The ordinary 

 tubercle has a rather dark ring surrounding the base of 

 the hair, and these special tubercles have also a dark ring 

 of just the same size, and perhaps a little darker tint. 

 This dark ring crowns a short conical column, and has 

 about 10 to 12 sharp points round its margin. Without 

 being at all like, they suggest the special tubercles of 

 Liniacodids. They are disposed one on either side of 

 each of the dorsal tubercles, so that tubercles I and III 

 with their eight attendant tubercles form a transverse row 

 of 12 nearly equidistant points, whilst in the case of II 

 the attendant tubercles are a little posterior to tubercles 

 II, and so do not quite fall into a row with them. 



There is a further very marked distinction between the 

 two species, ■pcnella having only 7 crochets to the prolegs, 

 whilst jm?'af^o,ra has 11. 



Paradoxa is larger than fcnclla, and hibernates in second 

 instar, penclla in third. 



In the full-grown larvae, not having them side by side 

 for comparison I may easily be at fault, but think there 

 is no other difference than that of size. 



The cocoons differ much in size and also in colour, that 

 of 'penclla being a pale lemon-yellow, of ixtradoxa a deep 

 reddish-orange. 



The male imagines are well defined by Rambur, Bruand, 

 and others, in their descriptions of the species. Penella 

 is smaller, darker, and much more densely scaled than 

 paradoxa. This is especially noticeable in the body 

 scaling. Paradoxa looks very thin and slight, and gives 

 very much the same impression of being without scales on 

 the thorax, whether they be absent or whether the some- 

 what evanescent and sparse clothing is still present, the 

 abdomen is but little better furnished, whereas peiiella 

 looks a solid, robust little fellow entirely in consequence 

 of his thick fleece. 



Penclla has a more robust-lookinof antenna, with longer 

 pectmations. The length of the pectinations persists till 

 towards the end of the antenna, whilst in paradoxa, the 

 shortening begins comparatively near the base. On both 

 36 pairs of pectinations may be counted ; these are almost 

 (^uite constant in paradoxa, but often vary to 32 in penclla. 



The anterior tibial spurs in p)cnclla arise near the middle 



TRANS. ENT. SOC. LOND. 1902. — PART IT. (dEC.) 48 



