HYDRACARINA 



93 



each side an outer row of 4 lateroglandularia and an inner row of 7 dorsoglandularia. The 

 first dorsoglandulare is also termed antennifonn. Between the just-mentioned two rows 

 there is a row of 4 chitinized shields, the dorsolateralia, and on the medial side of the dorso- 

 glandularia we find a row of 5 other shields, the dorsocentralia. Near the frontal organ 

 there can sometimes be distinguished two small shields on each side, viz., the prae- and post- 



FiGURE 3. — Protziella hutchinsoni gen. et sp. n. A, animal from above ( ? ) ; 

 C, frontal organ ( 9 ) ; D, maxillary organ from the left side ( $ ) ; E, mandible ( S). 

 side (9). 



B, frontal shield ( 9 ) ; 

 F, palp ( 9 ) ; G, ventral 



frontalia, and, outside of these, two bristles on each side, the prae- and postocularia. In the 

 Thyasinae there is a marked tendency to develop more or less strong and voluminous chitin- 

 ized shields, which either remain isolated from one another or coalesce in a different way in 

 different genera. 



It is of considerable interest to find that the family Protsiidae presents the same chitin- 

 ized skin-elements and dermal glands as just described in the Thyasinae, and this fact indi- 

 cates a rather close relationship between tiic two families. In Profsia, Calonyx and Partnuiiia 

 there are no skin-plates developed, but according to Walter (1919) there are some in the 



