25 



and there very densely armed with the curious lamellate denti- 

 cles or spines, which are so striking a character of the chelae 

 generally. Its articulation with the fourth is of such a character 

 as to afiford extreme mobility and there is also an extremely per- 

 fect articulation between it and the great claw, allowing the most 

 rapid closing and opening of this claw. 



The claw itself, forming the one-half of the chelae, is worthy 

 oi careful study. In Fscudogoiiatopns, Paragonatopus and 

 tiaplogonatopns, of the apterous forms, it is, except for the bent 

 tip, nearly straight and sub-parallel-sided, and always well armed 

 with the lamellate denticles beneath. It has always in addi- 

 tion a minute, but quite distinct, tooth on its lower side, very 

 close to the tip. 



In Gonatopus, Neogonatopus> Epigonatopus^ Pachygonato- 

 piis and Chalco gonatopus on the other hand, this claw is more 

 curved, subdilated basally, with its lower edge on that part sharp 

 and slightly convexly curved and the lamellate denticles are alto- 

 gether absent or very inconspicuous and ill-developed. 



EclUhrodelphax, Neodryimis, Paradryin\is, ChlorodryimiS' 

 and Thaiiinatodryiniis in all essential respects resemble Psciido- 

 gonatopns and the two allied apterous genera. 



Thus the genera with chelate tarsi form three groups: 



(i). The chelae imperfectly extensile, the claw strong and 

 nearly evenly curved, the lower edge nearly evenly concave; not 

 armed beneath, except sometimes with a basal angulation or 

 projection carrying a seta. The surface of the claw has a micros- 

 copic, longitudinal rugulose sculpture. 



(2). The chelae are perfectly extensile, the claw is long, 

 slender and less evenly curved, the curvature being chiefly on 

 the apical third or half. The claw is subdilated basally, its lower 

 ttdge not forming an even curve, but it is slightly convexly round- 

 ed on the basal half; lamellate denticles are altogether wanting or 

 are very few and ill developed and more like mere setae, and 

 there is no distinct microscopic tooth close to the apex. An 

 almost imperceptible angulation is sometimes seen further back 

 fiom the apex of the claw under strong magnification. 



(3). The chelae are perfectly extensile; the claw long and 

 slender and well armed beneath with lamellate denticles and 

 with a small but quite distinct tooth near the apex; it is nearly 

 straight and parallel-sided except that the tip is bent, and its 

 lower margin on the basal half is not at all convexly curved, 

 nor is the claw on that part subdilated. 



Of the species considered in this paper the only real exception 



