ON THE BRITISH SPECIES OF SIMULIUM II. 221 



11. Clypeiis with a single dark spot posteriorly, or none . . . . . . 12. 



Clypeus otherwise marked . . . . . . . . . . . . . . 13. 



12. A dark area in middle of posterior margin of clypeus, and another on each side 



of the head before the eyes , body colour greenish . . reptans, L. 



Head all pale ; body colour greyish . . . . . . . . tuberosuniy Ldst. 



13. A large black mark in the form of an H near the middle of the clypeus ; body 



colour yellowish-green . . . . . . . . . . morsitans, Edw. 



A pair of dark spots on clypeus, more or less connected anteriorly ; body colour 

 bright green . . . . . . . . . . . . venustum, Say. 



14. Gills branched ; clypeus with six dark spots, not always well defined ; " eye- 



brow " without dark dot . . . . . . . . latipes, Mg. 



Gills simple (at least in S. aureum) ; a dark dot in the anterior part oi the 

 *' eyebrow " . . . . . . . . . . . . . . . . 15. 



15. Clypeus with a median dark streak, more or less interrupted, and four other 



spots . . . . . . . . . . . . . . aureum, Fries. 



Clypeus with eight distinct dark spots, including two transverse bars at each 

 posterior corner . . . . . . . . angustitarsis, Ldst. 



16. Antennae very long, blackish, 9-jointed ; central tooth of mentum simple 



subexcisum, Edw. 



Antennae short, pale at least basally, 3- jointed ; central tooth of mentum 



strongly trifid . . . . . . . . . . hirtipes, Fries. 



Pupae. 



1 Pro thoracic respiratory organs in the form of thick tubes, the main branches 

 of which encircle the thorax at the nearly circular mouth of the 

 cocoon . . . . . . . . . . . . . . equinum (L. ) Edw. 



Respiratory organs consisting of a number of slender filaments . . . . 2. 



2. Respiratory filaments with numerous ultimate branches (50-60 or more) ; 



cocoon a loose shapeless network . . . . . . hirtipes, Fries. 



Respiratory filaments with not more than thirteen ultimate branches ; cocoons 

 closely woven and shaped like the toe of a slipper, usually with senii- 

 circular opening . . . . . . . . . , . . . . 3. 



3. Respiratory filaments eight . . 



six 



,, ;, four 



,, ,, thirteen . . . . . . tredecimatum, 



4. Cocoon with a long anterior dorsal projection : the upper two pairs of respiratory 



filaments with long vertical stalks . . . . . . yerhuryi, sp. n. 



Cocoon without anterior dorsal projection ; respiratory filaments otherwise 5. 



5. Filaments arranged in four shortly-stalked pairs . . . . . . . . 6. 



Filaments not in pairs ; all rather widely diverjzent close to the base, towards 



which 3 of them are noticeably thickened . . subornatum, sp. n. 



(713) c 



4. 



9. 



14. 



sp. n. 



