APPENDIX. 367 



3. S. fraterna. Deep black, polished ; abdomen black- 

 brown, opaque ; base of the poisers, and feet pale yellowish. 



Inhabits North-west Territory. 



t/intennae dark fuscous, with dense grayish hair ; eyes 

 in contact above the antennae ; thorax polished ; wings 

 dusky, pale yellowish at base ; poisers with a yellowish 

 scapus and fuscous capitulum ; feet dusky towards the tip ; 

 abdomen fuscous, opake. 



9 Length of the body one-tenth of an inch, % smaller. 



4. S. exigua. Black ; thorax piceous at the anterior an- 

 gles ; poisers whitish at base ; feet whitish, dusky at tip. 



Inhabits North-west Territory. 



Antennse fuscous, with dark gi'ay hairs ; wings a little 

 dusky; nervures {nscons; poisers elongated, whitish, capi- 

 tulum fuscous ; abdomen fuscous, opaque. 



% Length of the body one-twentieth of an inch. 



9 A little larger, with the base of the feet and of the 

 poisers of a darker shade than those of the male. 



SCATOPSE. 



5. atrata. Deep velvet black ; tarsi pale ; tip of the an- 

 tennaE! abruptly compressed. 



Inhabits Pennsylvania. 



Body hardly polished and nearly opaque, immaculate; 

 poisers colour of the body ; ivings hyaline: marginal ner- 

 vures but little more than half the length of the wing, fus- 

 cous ; furcate nervure attaining the tip; below the furcate 

 nervure are two parallel nervures which do not reach the 

 margin ; beneath the latter is the ordinary undulated ner- 

 vure. 



I obtained several specimens which were crawling on 

 the glass of a window, in September, in Philadelphia. The 



