MYRIAPODA 67 



Bollman. This animal is peculiar in the unusually great accentuation 

 of the sutures of the segments, which are marked by grooves visible 

 to the naked eye. 



TYLOBOLUS UNCIGERUS (Wood). 



Spirobohis uncigerus Wood, Proc. Phila. Acad. Sci., p. 15, 1864 ; Trans. Am. 

 Phil. Soc, xiii, p. 209, 1865. — Bollman, Bull. 46, U. S. Nat. Mus., p. 

 49. l8 93-/ 



The specimens studied by Bollman are in the National Museum, 

 and belong to this genus. As a species, T. uncigerus is more slen- 

 der than the two preceding, and may also be separated by the charac- 

 tei - s of the gonapods as shown in Wood's figure. The apex of the 

 ventral plate and the corners of the anterior lobes are much more an- 

 gular than in T. deses. 



A young female specimen in the National Museum collected by S. 

 C. Brown at Corvallis, Oregon, evidently belongs to Tylobolus, and 

 is more similar to T. uncigerus than to the other species. 



Onychelus gen. nov. 



Type. — Onychelus obustus sp. nov. 



Antennae accommodated by a shallow excavation of the head and 

 mandibulary stipe ; not concealed under the first segment. 



First segment distinctly emarginate on each side in front, to accom- 

 modate the very prominent posterior corners of the head. 



Second segment without ventral processes. 



Segments with a distinct transverse constriction, the posterior sub- 

 segment distinctly thicker and more convex than the anterior ; repug- 

 natorial pores located in front of the constriction ; pores followed on 

 posterior subsegments by a very distinct longitudinal sulcus. 



Anal valves strongly inflated, evenly convex, not more prominent 

 near the margins as in Tylobolus, not greatly exceeding the short, 

 broadly rounded apex of the last segment. 



Anterior legs of male with claws very large, as long as the distal 

 joint ; first two pairs strongly crassate ; legs 3 to 7 with coxae only 

 slightly produced; second joints with a rounded prominence below 

 distad ; other joints normal. 



Gonapods with ventral plate produced into a rather narrow tongue 

 nearly as long as the anterior lobes ; posterior gonapods slender, simple. 

 Seventh segment with a transverse ventral crest. 





