ON THE BRITISH SPECIES OF SIMULIUM — II. 219 



13. Claws simple and very large ; thorax witli three narrow black lines (hidden in 



good specimens by golden pubescence) . . . . equinum (L. ) Edw. 



Claws smaller and with a large basal thumb-like projection ; thorax unstriped 



14. 



14. Pubescence of thorax golden or brassy ; second hind tarsal joint deeply 



excavated . . . . . . . . . . . . . . 15. 



Pubescence of thorax and abdomen dull yellowish- white ; second hind tarsal 

 joint only shghtly excavated . . . . . . . . . . . . 17. 



15. Pubescence of abdomen very scanty, hairhke and whitish ; abdomen pink in 



Hf e ; legs nearly all black . . . . . . . . , . latiptb-, Mg. 



Pubescence of abdomen dense, scale-like and golden ; abdomen yellowish in 

 me •• •• •• •• * • •• •• •• J-O* 



16. Femora and tibiae clear yellow with black tips . . . . aureum, Fries. 

 Femora and tibiae darker, the latter with a dark ring close to the base 



angustitarsis, Ldst. 



17. Pubescence of thorax all pale . . . . . . .... suhexcisum, Edw. 



Pubescence of thorax with three dark stripes, the middle one divided by a line 



of pale hair-Hke scales . . . . . . . . . . yerbur/ji, sp. n 



Full-grown Larvae. 



1. Antennae 4, 5, or 6 jointed, though the division between the first two, three or 



four is somewhat obscure . . . . . . . . . . . . 2. 



Antennae 3 or 9 jointed .. .. .. .. .. .. ..16. 



2. Last abdominal segment rounded ventrally, or with only very small papillae ; 



antennae usually 5 jointed . . . . , . . . . . . . 3. 



Last abdominal segment mth a pair of large conical papillae ; antennae 

 4-jointed, but very long and slender . . . , , . . . . . 14. 



3. The three anal gills simple (sometimes with a few short branches in galeratum) 4, 

 Anal gills each with 5-10 branches* (4 or 5 in reptans) , . . . . . 9. 



4. Anal sucker with 100 or more rows of hooks, 18-25 hooks in each row . . 5. 

 Anal sucker with 65-80 rows of hooks, 12-18 hooks in each row ; body not 



bright green ; dark " eyebrows " present . . . . ♦.. . . 6. 



5. Central and lateral teeth of men turn enlarged ; head markings distinct, but dark 



eyebrow absent ; body bright green . . . . . . equinum, L. 



All teeth of mentum small ; head markings very indistinct, bat a dark eyebrow 

 present ; body colour uncertain . . . . . . tredecimatum, sp. n. 



6. Abdomen without distinct banding ; skin round anus with numerous minute 



trifid spines . . . . . . . . . . . . . . . . 7. 



Abdomen with a distinct dark band on each segment dorsally ; skin round 

 - . anus nearly bare . . . . . . . . . . . . . . . . 8. 



* When the gills are branched they are much less frequently retracted than when they 

 are simple. The gills of 8. subornatum have not been observed ; since they were retracted 

 in aU the specimens examined, they are probably simple. 



