TRÄGÅRDH, MORPHOLOGY AND PHYLOGENY OF FARASITID^. 5 



In the nymphae of most of the Uropodince there are also 

 more than 2 dorsal shields; generally either 3 or 4. The 

 pattern is different from that of Sejns and Liponyssus, but 

 is easily deduced from that. 



In the nympha of Uropoda tecta Kr. [1. fig. 6. pl. 157] 

 there are, aceording to Berlese, 4 dorsal shields; one large 

 anterior one, projecting far backward, with narrow rounded 

 top; at the hind margin a smaller, transverse-oval shield 

 rounded anteriorly and in the angles between the two there 



r^" 



Fig. 



Fig. 8. Uropoda tecta Kr. nympha (after Berlese). 

 Fig. 9. Discopoma romana Berl. nympha (after Berlese) 



is a pair of reniform shields (Fig. 8). In the nympha of Disco- 

 poma romana Berl., the two median shields have coalesced, 

 but the small lateral shields remain [1. fig. 4, pl. 162] (Fig. 9). 



It is easy to derive this type from the Sejus, if we as- 

 sume that the two pairs of small plates of Sejus in Uropoda 

 tecta have coalesced into one (Fig. 8); and finally the two 

 median ones have become fused in Discopoma. 



As a result of this snrvey of the comparative morpho- 

 logical and ontogenetic data gathered regarding the dorsal 

 shields of the Parasitidce, I think we may safely conclude 

 that in that family there is a strong tendency to coalesce the 



