igil] NORDAMERIKANISCHE HyDRACHNIDEN. 295 



short, stout, bipectinate bristles. All the other palpal bristles are un- 

 branched. On the third segment, particularly upon the extensor sur- 

 face is a number of extremely stout, long and bent bristles, upon which 

 the specific name setosa is founded. The fourth segment is thickened at 

 the outer end and is provided, on the inner side, with a long, acute, chit- 

 inous spine. The extremity of the palpus bears two or three larger 

 claws, lying close to one another, and at the base of the dorsal claw is 

 another considerably smaller one, which is noticeably bent. 



The epimeral region is 863/1* long and leaves the ventral abdominal 

 surface uncovered to a distance of 58 1/*. The maxillary emargination 

 is 240/Lt long, the genital emargination 215/u long, the posterior end of the 

 second pair of epimera 41/* broad, the median suture of this pair of plates 

 200/t long. The posterior dividing furrow between the second and third 

 plate is strongly bent inwards. The last epimeron is noticeable for its 

 narrowness and is bordered by a broad poreless margin ; this is continued 

 forward on the outer side of the third plate as a still broader marginal 

 zone. 



The legs are robust, porous and strongly chitinized. The three 

 posterior pairs are remarkably expanded at the distal extremity. The 

 ungues of the posterior pair are 80/^ long, the ungual plate (Krallenblatt) 

 of little breadth, the accessory tooth not long but stout. The front leg 

 is as long as the epimeral shield; the hind leg has a length of 1543/u. and is 

 thus shorter than the body. With the exception of the first pair the 

 legs are richly supplied with bristles and, in fact, chiefly with stout 

 spinous ones, especially at the outer end of the femur and the patella 

 of the three posterior pairs of segments. A few of the bristles are leaf- 

 like, attaining a breadth of 12/*. Swimming hairs are wanting. 



The valves of the external genitalia measure 232/i. The latter extend 

 a considerable distance back out of the epimeral emargination which, 

 in consequence of the marked narrowing of the last epimera, is noticeably 

 shortened. The inner margin of the valves bears a number of stiff 

 and crooked bristles. The two posterior pairs of acetabula are shorter 

 and broader than the most anterior (Fig. 20). 



The anal opening lies somewhat near the hind margin of the body, 

 separated by 415'^ from the genital area (Fig. 20). 



Locality: — Canada (without further data). 



Explanation of Plates. 

 Plate I. 



Fig. I. Eylais falcata Koen. Eye-plate, viewed from beneath. From 

 preparation 115. Obj. 3X0C. 4X20 cm. tub. (X135). 



