1914.] NATURAL SCIENCES OF PHILADELPHIA. 647 



derived from Professor Melander's given name, to serve as an indica- 

 tion of this probability. It seems inadvisable to assume identity, 

 as it is improl^able that it can be proved, and since the insects appear 

 different, it is desirable to know which is referred to in any particular 

 citation. When describing P. melanderi I remarked on the lengthen- 

 ing of the stem of the fourth vein, between the anterior cross-vein 

 and the fork. In P. plagiata Wied. (det. Knab) from Quirigua, 

 Guatemala (W. P. Cockereir),it is exactly as long (752 microns) as 

 in P. axeliana. P. plagiata, however, differs radically from P. axeliana 

 and melanderi in having the second vein (or upper branch of third) 

 directed vertically upward, so that it looks like a cross-vein. 



Bibio wickhami n. sp. (Bibionidse). 



9 . Length about 12 mm. ; wing 6.75 ; proboscis 2 mm. ; hind 

 femur 3 mm.; second posterior cell slightly over 2.5 mm. long. 

 Head, thorax and legs black; abdomen dark brown, the sutures 

 colorless; wings clear, the costal region slightly brownish, veins pale 

 reddish. The stem of third vein, before the cross-vein (following the 

 usual interpretation) , is 576 microns long, while the cross-vein is only 

 about 80. The cross-vein leaves the fourth at a slight angle, and is 

 in a straight line with the part of the third (2 + 3) beyond it, the 

 third being abruptly bent at the cross-vein. This is nearly as in the 

 living Bibio alhipennis, but is very different from the Florissant fossil 

 B. atavus, in which the stem of fourth before the cross-vein is only 

 about 320 microns, while the oblique cross-vein is about 1,040, being 

 almost as long as the stem of fourth vein between the cross-vein and 

 the fork (basal corner of second posterior cell). 



Miocene shales of Florissant, Wilson Ranch (Wickham). 



Mycomya lithomendax n. sp. (Mycetophilidse). 



Length nearly 5.5 mm., abdomen 4, wing 4 mm.; anterior tibia 

 about 1.5 mm., its tarsus 2.5; microscopical measurements give the 

 following in microns: anterior tibia, 1,392; its basitarsus, 1,120; 

 length of antennse, 1,920. Dorsum of thorax and abdomen dark 

 brown, the abdominal sutures rather broadly pallid; tibiae and tarsi 

 brown, femora pallid; hind femora with a row of short black bristles 

 on under side; wings redcUsh hyaline, without markings. The 

 thorax (seen in lateral profile) is much more elevated or humped than 

 in M. cockerelli Joh. The venation nearly agrees with that of 

 M. cockerelli, but differs in some small details. The subcosta 

 (I follow Johannsen's nomenclature) ends on the costa as usual, its 

 upwardly directed end, beyond the cross-vein, is 128 (all measure- 

 ments in microns) long; the cross-vein to radius is 192 beyond base 



