18 ARKIV FÖR ZOOLOGI. BAND 7. NIO 28. 



of them, this shielcl has only 4 pairs of hairs; the epig3niial 

 one of the female none. 



If we compare this with the ontogeny, \ve find in the 

 nympha of Parasitus hoynhorum DG (Fig. 27) for instance, 

 5 pairs of hairs on the intercoxal part of the belly; b ut of 

 these only 4 pairs are inserted on the sterniti-meta- 

 s tern al sliield; and the same is the case in all nymphae, 

 except those of the Urofodince',^ but in that group the long 

 rectangular shield is certainly not homologaous with the 

 sterniti-metasternal shield of the other. 



The result of this examination we may formulate thus: 

 On the ventral side of the II — IV prosomatic segments there 

 are only 4 pairs of hairs, and these do not belong to the 

 so-called endopodal shields, but to the sternal and meta- 

 sternal shields. 



When hairs occur on the epigynial shield, the reason of 

 this is that the shield is fused with some other shields or 

 trichoferous elements of the opisthosoma. 



This view is also suggested by Oudemans [11. p. 6] when 

 describing the larva of Parasitus iota Oudms. He says: 

 »Between the coxse 3 pair of bristles, apparently belonging, 

 hke the legs themselves, to the 3rd, 4th and 5th postoral 

 segments. These bristles afterwards will be placed on 

 the sternal shield. Behind the coxse III a pair of bristles 

 belonging to the 6th postoral segment, which in future will 

 bear the legs IV. This pair of bristles will afterwards 

 be placed in the metasternal shields, if the larva 

 becomes a female. Behind this pair another one which 

 belongs to the 7th postoral segment and which will be 

 implanted in the genital shield if the larva becomes 

 a female. 



1). Evidence of tlie hairs. 



It seems hardly possible that the conformity in number 

 of hairs and segments is nothing but a coincidence. In my 

 opinion it signifies that the 4 pairs of hairs are the (only) 

 remnants of an otherwise supprcssed segmen tation. 



Of this segmentation there is now very little left, since 



In the nympha of Urosejus there are, however, only 4 pairs. 



