96 



HYDRACARINA 



In the male the epiineral groups are more crowded and the space between them is nearly 

 filled up by the genital organ, whereas they are more distant in the female, leaving plenty of 

 space between each other and the genital organ. 



In both sexes some few bristles are scattered between the acetabula in the anterior part 

 of the genital field, and the excretory opening is surrounded by a ring of chitin. 



Nymph. Like the adult the nymph is recognized by the prolonged last leg. In the only 

 specimen examined the genital organ consists of four acetabula on the right and three on the 

 left side. Judging from the situation of the acetabula probably three acetabula on each side 

 is the rule. 



Figure 5. — Protziella hutchinsoni gcMi. ct sp. n. Genital organ of nymph. 



Locality. Indian Tibkt: Shimsha Karbu between Dras and Kargil (K78), 22 May, 

 1932, in a spring (temp. + 8°C., pH. 7.8), altitude ca. 2819 m. ; springs (temp. + 7.2='C.) 

 4 miles from Bao, between Bao and Drugup (L35), altitude c. 4100 m., 26 June, 1932. 



Systematic affinities. The genus Protziella differs from all other Frotziidac in a series of 

 characters, viz. : (1) the strong chitinization of the dorsal surface, a well-developed frontal 

 shield (and small dorsocentralia and dorsolateralia) being present. (2) the well-developed 

 frontal organ, with its double spot of pigment; (3) the non-stipitate acetabula, situated out- 

 side the genital plates. 



In some of these characters the genus more resembles certain ineni])ers of the subfamily 

 Thyasinae than the Protsiidae. Very often the dorsal surface of the body is more or less 

 chitinized in the Tliyasinae, and in some genera there is, as already mentioned, a double pig- 

 ment spot. The non-stipitate acetabula also gives the animal an appearance somewhat 

 unfamiliar to a Protziid and more in correspondence with that of a Thyasin."' The situation 

 of the acetabula outside instead of inside the genital plates is, however, a character unknown 

 in both groups. 



Like Eutliyas and Thyasides among the Tliya.<:iiiac — both with two spots of pigment 

 in the frontal organ — Protziella seems to occupy quite an isolated position among the 

 Protziidae. It has been already mentioned that in some respects — chitinization of dorsal tody 

 surface, frontal organ, non-stipitate acetabula — Protziella resembles certain Tliya.<;iiiae, but 

 probably this agreement is to be explained by convergence. However, it is impossible to 

 deny the affinity of the Protziidae and the Thyasinae (or 1 1 yd rypJwntidae) . W'c find another 

 similarity between the two groups in the complicated claws which Viets recently (1929) has 

 described in the aberrant genus Tcratothyas, belonging to a special subfamily, Teratothya- 

 sinae, among the liydryphantidae. The claws in that genus are said to be like those of 



'^ It must be remembered, however, that according to Walter tlic acetabula in Catonyx hilus arc non-stipitate. 



