T. D. A. Cocker ell — Descriptions of Tertiary Insects. 53 



Art. III. — Descriptions of Tertiary Insects ; by T. D. A. 

 Cockerell. Part V. 



Some New Diptera. 

 Lasiosoma mirandula sp. nov. (Mycetophilidse : Sciophilinse). 



Expanse 16 mm ; length of body about 10 mm , of wing 7 mm ; 

 abdomen reddish, with the hind margins of the segments rather 

 broadly blackened, its whole surface with minute appressed 

 hairs ; legs pale brown, the femora minutely hairy ; wings 

 wonderfully preserved, strongly rufescent, with a purple or 

 pink tinge, nervures darkened. By the dusky wings and the 

 short prostrate hairs on abdomen it agrees with the living I. 

 pallipes (Say), but it is considerably larger than Say's species. 

 The venational features are as follows : the costal thickening 

 extends a short distance beyond the tip of the ultimate branch 

 of the radius (third vein) ; subcosta, much as in the fossil 

 Sciophila hyatti Scudd., does not distinctly reach the costa, 

 but is evanescent after the little vein which passes from it to 

 the radius, meeting the beginning of the inferior branch of the 

 latter ; small vein from costa to subcosta distinct, oblique, 

 forming an angle of 45° with each, and placed a moderate dis- 

 tance (about f mm ) from base of wing ; branches of radius as in 

 Sciophila, with the same little cell formed in the fork by 

 R 2+3 running up to join E, a : media, as usual, weaker than 

 radius, and forking almost immediately after leaving the radio- 

 medial cross-vein, so that the stem before the fork is shorter 

 than the cross-vein, although the latter is short and not very 

 far from vertical ; cubitus forking not far from base as in 

 Sciara / anal with its apical portion wanting, as in Ceroplatus. 

 In Williston's tables (N. A. Diptera, 3d ed.) this runs exactly 

 to lasiosoma, and seems to accord well with that genus.* The 

 living American species are northern. 



Hah. — Florissant, Colorado, in the Miocene shales, Sta. 14 

 {S. A. Rohwer, 1907). 



Holotype in Peabody Museum (Yale). 



Tetragoneara peritida sp. nov. (Mycetophilidse : Sciophilinss). 



Length 4 mm ; wing 3-f, antenna l| mm ; dorsum of head, tho- 

 rax and abdomen dark brown, the rest of the body pallid ; 

 legs long and slender; wings hyaline, with brown nervures. 



*It differs, however, from Handlirsch's figure (Foss. Ins., pi. vi) of Lasio- 

 soma in the shorter subcosta, not ending on costa, and also in the more ver- 

 tical radio-medial cross-vein. Handlirsch's figure does not show any cell in 

 the forks of the radius, so it may not be of this genus. 



