EMBTOPTERA OF THE NEW WORLD ROSS 449 



tive cerciis, and since species of the genus Anisembia have much more 

 generalized terminalia than any Chelicerca, it appears that the one- 

 segmented condition was attained independently in the two genera. 



The component subgenera, Protochelicerca, Chelicerca, and Dac- 

 tyJoccTca^ seem to form a very natural evolutionary series, exhibiting 

 increasing specialization of the abdominal terminalia (e. g., the left 

 cercus), which seems to be directly derived from more primitive 

 genera of the south such as Schizenibia. 



The specialization of the left cercus corresponds with a serial 

 specialization of other terminal abdominal structures in the species 

 and with the degree of their geographic separation from the region 

 of probable origin (northern South America). The most specialized 

 species of the series, rubra, occurs in the Sonoran region of North 

 America, which has probably presented more selective environmental 

 changes than the Tropics. 



KEY TO SUBGENERA AND SPECIES OF CHELICERCA (MALES) 



1. Left cercus l-segmented 2 



Left cercus 2-segmentecl C. (Protochelicerca) dampfi 



2. Right bemitergite produced caudad as a distinct process bearing 1 or 2 



outwardly curved, clawlil^e books ; left cercus not greatly elongated or very 



strongly inwardly arcuate (subgenus CheUcerca, s. str.) 3 



Rigbt bemitergite not produced caudad as a process and not bearing claw- 

 like apical books; left cercus greatly elongated, strongly inwardly arcuate 



C. (Dactylocerca) rubra 



3. Process of rigbt bemitergite witb but 1 outwardly curved, clawlike apical 



book 4 



Process of rigbt bemitergite witb 2 sucb books C. (Chelicerca) heymonsi 



4. Apical hook of process of rigbt bemitergite arising on inner side of process 



and curving across its apex C. (Chelicerca) wheeler! 



Apical hook arising terminally, not overlapping any tergal structure 5 



5. Left apical angle of process of bypandrium (HP) produced as a distinct, 



tbumblike, densely echiuulate knob C. (Chelicerca) nodulosa 



Left apical angle of process of bypandrium (HP) less strongly produced, 

 pointed, without ecbinulations C. (Chelicerca) davisi 



Subgenus Protochelicerca, new subgenus 



31ales. — Eather large, winged. Head larger than terminalia ; eyes 

 very large, inflated; occipital foramen evenly rounded apically. 

 Wings large, broad ; Ri narrow, closely paralleling costal margin and 

 meeting it apically, apex not joining E0+3 by means of a cross vein ; 

 three cross veins present between Ri and R0+3 in forewing, two in hind- 

 wing. Terminalia very similar to those found in CheUcerca, s. str., 

 but with the left cercus distinctly two-segmented, the terminal segment 

 rather small, broad basally. 



Type. — Chelicerca {Protochelicerca) dampfi, new species. 



Distribution. — That of the single species. 



552731—43- 4 



