NORTH AMERICAN DIPTEKA. 158 



42. — An inner marginal cell present, which is short, broad and nearly triangular ; 



discal cell absent Cryptolubis. 



Inner marginal cell either wanting l^no marginal cross-vein), or elongate 



and much longer than wide 43. 



43. — Fork of second vein very short and the anterior branch moderately steep, 

 the outer marginal cell thereby small and almost in the form of an 



equilateral triangle 44. 



Fork of second vein long, the anterior branch almost parallel witli posterior 



and the outer marginal cell in consequence much extended in length. .45. 



44. — Marginal cross-vein preseut, connecting first vein with praefurca of second 



considerably before furcation of latter Empeda. 



No marginal cross- vein Gonoinyin. 



45. — Marginal cros.s-vein situated well beyond furcation of second vein 47. 



Marginal cross-vein situated immediately after furcation of second vein. .46. 

 46. — Auxiliary vein terminating before marginal cross-vein. ..Ciiiophomyia. 



Auxiliary vein terminating beyond marginal cross-vein Triinicra. 



47. — Posterior branch of fourth vein not forked (four posterior cells present). .48. 

 Both branches of fourth vein forked (five posterior cells present). 



Cladura. 

 48. — Great cross-vein far anterior to origin of second vein ; legs long, very slen- 

 der and delicate Diotreplia. 



Great cross-vein far beyond origin of second vein* Sigiiiatoiiiera. 



49. — Antennae 6- to 10-jointed (subfam. Anisomerina) 50. 



Antennas at least 13-jointed, but usually 16-joiuted 52. 



50. — Discal cell wanting Aiiisoinera. 



Discal cell present 51. 



51. — Subcostal cross-vein a short distance before tip of auxiliary vein, the mar- 

 ginal cross-vein a short distance before tip of first vein Eriooera. 



Subcostal cross-vein at very tip of auxiliary vein, the marginal cross-vein 



more distant from tip of first vein Pentlioptera. 



52. — Subcostal cross-vein at about middle of wing and always before origin of 



second vein (subfam. Amalopina) 53. 



Subcostal cross-vein situated be,yond middle of wing, and always beyond 



origin of second vein (subfam. Limnophiliua) 58. 



53. — Antennae 13-jointed 54 



Antennae 16-jointed 56 



54.— Two marginal cross-veins present, atid therefore three marginal cells, the 



innermost marginal cell short and broad Dicraiiota. 



Only one marginal cross-vein, inner marginal cell elongate ,55. 



55. — Both branches of fourth vein forked Rliaphidolabis. 



Anterior branch of fourth veiu simple, posterior branch furcate. 



Plectroinyia. 



56. — Whole surface of wings finel.v pubescent I'la. 



Wings naked 57 



57. — Small cross-vein at a right angle with longitudinal axis of wing ; last .joint 



of palpi not longer than two preceding joints together .4nialopis. 



Small cross-vein at a very oblique angle with longitudinal axis of wing, 

 and in one line with great cross-vein ; last joint of palpi longer than 

 the three preceding joints together I*e<iicia. 



* Although this cannot actually be gathered from the description, it is universal 

 so far as I can find in the group to which this genus belongs. 



TRANS. AM. ENT. SOC. XIX. (20) JUNE, 1892. 



