igil] NORDAMERIKANISCHE HyDRACHNIDEN. 283 



seen from above has a very long oval form. The lack of a distinct 

 chitinous arch in the posterior part of the pharynx is noteworthy. 



The tracheal plates are 500-530/* long. In dorsal view they present 

 a thickened anterior and an expanded, shovel-shaped posterior extremity. 

 In lateral view they appear very stout, the posterior end with a long and 

 strongly falciform upward curve. 



The mandible is 250-340/A long and attains a breadth of 200//. It 

 is markedly narrowed caudad. The flexor side presents a marked short- 

 ening. The angle of the hind margin of the extensor side projects some- 

 what. On the strongly receding opposite angle is the stigmatal papilla 

 which is quite broad at base. The claw of the mandible is strongly bent, 

 thickened at its distal extremity and very densely chitinized. 



The maxillary palpus measures fully looo/t in length, and its segments, 

 taken in series from the first to the fifth, measure as follows: 99, 199, 166, 

 381 and 182/4. The second segment, whose cuticle is soft on the flexor sur- 

 face,has a series of 6 to 8 short,closely pectinate bristles. On the stout round- 

 ed prominence on the flexor side of the third segment is a group of numer- 

 ous short spinous bristles, on the middle of the inner anterior margin a 

 moderately long, fine hair, and in the corresponding situation on the outer 

 anterior margin a short, strong, pectinate bristle, whose branches be- 

 come gradually longer and stouter from the tip proximad. The outer 

 side of this segment shows near the margin of the flexor surface an opening 

 of obovate form. On the inner side the penultimate segment bears a 

 longitudinal row of four short ensiform bristles and a group of stouter 

 pectinate bristles on the distal margin ; one of the ensiform bristles is, as 

 a rule, shifted from the row towards the extensor side of the palpus. On 

 the outer side of the same joint is a row of four stout ensiform bristles, 

 of which the three posterior arise near the margin of the flexor surface, 

 while the most anterior, on the other hand, is shifted perceptibly away 

 from the latter margin forward. Close to the second bristle of this row 

 between the two longitudinal rows of bristles is another stiff, moderately 

 long bristle, strongly bent forward. At the tip of the terminal segment 

 is a number of very short spines (Fig. 3). 



The egg has a globular form and a diameter of 116/4. 



Locality, Rideau, from a pond. 



Eylais desecta Koen. 

 Syn. Eylais extendens Koenike, Abh. Nat. Ver. Bremen, 1895, S- ^7^- 



Eylais desecta Koenike, Abh. Nat. Ver. Bremen, 1897, S. 288. 



Female. 



The eye capsule measures 158/4 in length, 249/4 in breadth. The 

 anterior and posterior ends of the capsule are rounded off, though the 

 outer angle of the latter forms a slight prominence. The outer side of 



