416 bulletin: museum of comparative zoology. 



stream, females with young still in the nest, partly grown young as 

 well as many isolated adults being taken. This seems a favorite 

 location for them, at any rate during the summer season. 



This is a wide-spread species in the northern as well as in the south- 

 ern states; but in the latter region it is by no means so common as 

 A. bipuncticcps, G. umbraticus, G. mordax, or even A. watsingus. 

 Where found, however, a considerable number of specimens were 

 usually secured, the individuals almost swarming in several limited 

 areas. The specimens secured are all small, like those of Austria- 

 Hungary as described by Dr. Latzel; they vary from 15 to 35 mm. 

 in length with but few approaching the upper limit, the greater num- 

 ber by far being under 25 mm. The number of legs in the specimens 

 that were examined for this feature ranged from 41 to 47 pairs. 



Arenophilus, gen. nov. 



Prebasal plate not evident; frontal suture absent. Basal plate 

 trapeziform, strongly narrowed cephalad. 



Labrum, free, tripartite; the middle piece fully separating the lat- 

 eral, armed with a series of small teeth or teeth-like processes; the 

 lateral pieces with a fringe of numerous long, slender spinescent 

 bristles or processes. 



First maxillae nearly as in Geophilus; the coxae completely fused at 

 middle and separated from distal divisions by suture; palpi, Particu- 

 late, coxae and femora with long membranous lappets at distal 

 external angles. 



Second maxillae without pleurosternal sutures; palpus Particu- 

 late, without processes at distal end of femur. 



Coxosternum of prehensors without chitinous lines or but weakly 

 indicated. Prehensorial feet large, much exposed from above, extend- 

 ing cephalad well beyond anterior margin of head; articles distinctly 

 denticulate within. 



Ventral pores condensed, in definite areas, numerous. 



Last ventral plate, wide. Coxopleural pores aggregated and open- 

 ing into two large pits on each side which are mostly covered in whole, 

 or in part, by the last ventral plate. 



Anal pores present. 



Anal legs unarmed; at distal end a very small seventh article. 



Type. — Geophilus unaster Chamberlin. 



Three species from the present region are referable to this genus. 

 They may be separated as follows. 



