AEKIV FÖR ZOOLOGI. 



BAND 7. N:o 28. 



Contribiitions towards tlie comparative Morplio- 



logy and Pliylogeny of tlie Parasitidai 



(Gamasidae) 



by 



IVAR TRÄGÅRDH D. Se, F. E. S. 



Experimentalfältet, Sweden. 



With 30 textfigures. 



Communicated December 6th 1911 by Chr. Aurivillius and Y. Sjöstedt. 



Diiring my work on the Parasitidce, problems of a com- 

 parative morphological and phylogenetical natiire have oc- 

 casionally arisen; and in my previous papers on acari I have 

 also occasionally touched upon such questions. 



Thus, in the genus Trachyies the presence of well deve- 

 loped metasternal shields, the remarkable shape of the jugu- 

 lar shields, and the taxinomio value of these features have 

 been pointed out [16. p. 446—447]. Further, the bearing 

 of the number of hairs found on the sternal sbield on the 

 question as to the so-called metasternal shields being fused 

 with it or not has been suggested [16. p. 427], and the dif- 

 ferent composition of, and consequent non-homology between, 

 the genital shield of the UroiJodince and that of most other 

 Parasitidce has been pointed out [17. p. 600]. 



It has now been thought expedient to publish a short 

 summary of the results to which my studies have hitherto 

 led me; this purpose might, however, have been delayed, 

 until I had had an opportunity of studying still more material 

 of the group, but for the fortunate circumstance, that last 



Arkiv för zoologi. Band 7. K:o 28. 1 



