March. 19^1.) Cn AMBERI.I.V : Ll N YI'H I IDAE OF AlASKA. 39 



median eyes smaller than the laterals. Area of median eyes longer than wide 

 (10:9), wider behind than in front in the ratio 4:3. Anterior median eyes 

 much smaller than the laterals and much nearer to each other, being about 

 their radius apart but more than their diameter from the laterals. Clypeus a 

 little higher than length of area of median eyes. Upper margin of furrow of 

 chelicera with five large teeth ; lower margin with a series of close-set minute 

 teeth situated well toward base of fang. Details of palpus as shown in figs. 

 8, 9, and 10. 



Female. — Epigynum as shown in fig. 7. 



Length of cephalothorax of male type, i mm. : width, .8 mm. 



Length of tib. + pat. I, .8 mm. : of tib. + pat. I\', 1 + mm. 



A. ))u-miica (Koch) differ.^ in the more widely .separated eyes of 

 the posterior row. The male ditters ohviou.sly in the cliaracter.s of 

 the pal])us as e.g.. in the median dorsal apo])hysis of the tibia, which 

 is much more slender and has on each side another process of char- 

 acteristic form. 



Genus Arctilaira new genus. 



Agreeing with I'topiclliim Strand in the form of the cephalo- 

 thorax. The latter in the male is similarly depressed between and 

 caudad of the eyes in front of the cephalic elevation. Po.sterior row 

 of eyes strongly procurved. the eyes widely separated. Lateral eyes 

 prominently elevated on common tubercles. Upper margin of furrow 

 of clielicera with five teeth of which the ui)i)crmo.st is reduced, the 

 lower margin with three small, often granular, teeth, the dentition 

 alike in the two sexes. Chelicera of male not armed in front. Meta- 

 tarsi of leg I in the male curved and strongly spined. Tibia of male 

 palpus much thicker than patella, enlarged distad, at distal end a1)ove 

 with a very prominent i)rolongation above the tarsus. Third division 

 of bulb witli a prominently elevated and more or less complicated 

 lobe which extends to or beyond the tip of the cymbium. Ei^igynum 

 short and l)road. not i)rolonged freely behind the ejiigastric furrows. 



Genotype. — ArctUaira bclluiis sj). nov. 



The genus is quite obviously nearest I'tof^icllttw {.Strand, lyoi ), 

 which was established with the Erigonc wirahilis of Koch as geno- 

 type, but in the structure of the copulatory organs in particular is 

 quite di.stinct. In I'topicUttm the terminal lobe of the bulb of the 

 male palpus, so con.spicuously developed in Arctilaira and Ifilaira. is 

 obsolete, thus leaving the di.stal part of the alveolus empty and freely 

 exposed: while there is present across the distal end oi the bulb and 



