TRAGARDH, MORPHOLOGY AND PHYLOGENY OF TARASITID^. 



19 



the 3 first segments are generally fused witli one another; 

 but the 4th and last one lias still maintained its indepen- 

 dence in many genera, as the metasternal or paragynial shield 

 of the females. That only this segment has escaped being 

 fused with the other, is probably due to the circumstance 

 that it forms the anterior börder of the genital apertnre and 

 must therefore be movable to some extent. Probably in the 

 most primitive Parasitidoe the other 3 segments were also 

 represented by a pair of separate shields each; this assump- 

 tion is supported by the fact that in some forms the shields 

 are not fused, but still free. 



Thus in the female of Ologamasus inornatus Berl. (Fig, 28) 

 the last segment but one is separated from the two anterior 

 ones by a line running across 

 between the hind margin of coxse 

 II. There is no hne in the middle, 

 but a t the anterior margin of the 

 sternal shield there is a narrow 

 median incision extending back- 

 wards beyond the middle, and 

 p os si bly a primitive feature. 



Still more interesting featu- 

 res exist in Sejus togatus (K.), 

 where in the female the 3rd and 

 4th segment has a pair of di- 

 stinct shields, each with its hair; 

 and in the male the 3rd segment 

 has a pair of distinct shields. There are also other genera 

 in which the traces of segmentation ha ve not disappeared, 



Fig. 28. Ologamasus inornatus 



Berl. 9. Sternal and genital 



shields (after Berlese). 



Fig. 29. 



Fig. 30. 



Sejus togatus (K.). 

 Fig. 29. Sternal and genital shields, 9 X 100. 

 Fig. 30. » » " » o" X 100. 



