220 



r. W. EDWARDS. 



7. 



8. 



9. 



Head markings as in fig. la ; anal spines very numerous and dark 



ornatum, Mg. 



Head markings as in fig. Ic ; anal spines less numerous . . suhornatumy sp. n. 



Back of head with a large roundish black area . . reptans, var. galeratum, n. 



Back of head with four elongate dark spots, usually enclosed in a suffused 

 brownish area . . . . . . . . argyreatum, Mg. 



Larger species ; gills with 8-10 branches ; abdominal banding inconspicuous 

 or absent ; dark *' eyebrow " usually conspicuous ; clypeal markings of 

 the ornatum type though often indistinct (cf. also subornatum, with 

 different head marking) . . . . . . . . . . . . . . 10. 



/ A^^Wv^-^ 



/y ^-"^-/.A^V^ 



\ 



Fig. 2. Apex of mentum of Simulium larvae ; 

 all X 150. a, 8. ornatum ; h, S. subornatum ; c, 

 S. reptans ; d, 8. equinum ; e, 8. latipes ; /, 8. subex- 

 cisum ; g, 8. hirtipes (after Malloch) ; h, 8. tredeci- 

 matum. The hairs on the sides of the mentum are 

 not shown, but are of diagnostic importance, as 

 described in the text. 



10. 



Fig. 3. Antennae of Simulium larvae ; all 



X 50. a, 8. ornatum ; h, 8. subornatum ; 



c, 8. equinum ; d, 8. latipes ; e, 8. subexcisum ; 



/, 8. hirtipes (this last after Johannsen). 



Smaller species : gills with 4-6 (rarely 8) branches ; abdominal banding usually 

 conspicuous ; dark " eyebrow " usually absent ; clypeal markings various 

 but never of the ornatum type . . . . . . . . . . . . 11. 



Thoracic proleg with strong chitinisations behind the circle of hooks . . . 



variegatum^ Mg. 



These chitinisations much less evident ; skin round anus with more numerous 

 scales . . . . . . . . . . . . . . monticola. Fried. 



