1909] New Fossil Insects from Florissant, (Colorado 255 



(1) Stem of second and third veins (from first to divarication) 

 only about 1020 n long, and leaving first at a somewhat larger angle; 

 fork much wider, so that at about 2800 ix from the fork the second and 

 third veins are about 1055 /( apart. 



(2) For the length of 2S00 the third vein, very clearly visible, 

 shows no sign of the cross- vein to the fourth, but at this point (where 

 the break occurs) the fourth begins rapidly to ascend, showing that 

 the cross-vein is very little beyond. It results from this that the first 

 basal cell is extremely long, a character of the Mydaid^. 



(3) The fourth vein before the discal cell is not in a straight line 

 with the part bounding the upper side of the cell, there being a very 

 decided bend. 



(4) The junction of the discal and second basal is longer, about 

 1870 /{. (The cross formed at the lower basal corner of the discal cell, 

 and the adjacent parts toward the anal, are exactly as in Microstyhim.) 



(5) The anal cell is narrowly (170 //) open. 



(6) The fifth posterior cell has its upper apical corner cut off by 

 the deflection (to reach the margin at an acute angle) of the terminal 

 section of the fifth vein. This condition is approached in Mydaidas, 

 and slightly in some Apioceridae. 



(7) The vein which bounds the outer (marginal) side of the 

 closed fourth posterior cell, which in the Asilinae is directed upwards 

 from the lower corner of the cell, but in Microstyhim is approximately 

 parallel with the margin, is actually directed, though very obliquely, 

 toward the wing-margin, being broken (through the fracture of the 

 specimen) after a course of 800 /Jt, when 170 /( from the margin, its 

 beginning being about 510 //. from the margin. I cannot find any genus 

 showing this character, or any nearer approach to it than Microstyhim . 



Habitat. — Miocene shales of Florissant, Colorado, 1909 (117/- 

 lard Rusk). A true Microstylum (M. wheeleri Ckll.) has been 

 described from the Florissant shales. In addition to the original 

 type, we have now also a specimen found by Mr. Geo. N. Rohwer 

 in 1907 at Station 14. 



Nicocles miocenicus n. sp. (Asilidce; Dasypogoninas.) 



Length l.'U mm.; wings 9; length of abdomen \)\; its breadth 

 2^/5; hind femur about 4 mm.; black, rather robust, the abdomen 

 cylindrical, formed as in A^ cemulatar Loew; wings faintly dusky, not 

 appreciably spotted; legs robust, including the tarsal joints; hind tibia 

 much longer than its femur; hind basitarsus about 1440 ,« long and 

 580 broad; thorax and abdomen without visible hairs or bristles; 

 femora not visibly hairy; face with some bristles. In the following 

 account of the venation, comparison is made with Williston's figure 

 of Nicocles rufits (N. Am. Dipt., p. 194) and Verrall's of Dasypogon 

 teutonus (British Flies, v. p. 708). 



Auxiliary and first veins normal, thickened, their terminations 

 about 2720 (this and the following measurements in microns) apart. ' 



Second vein with a gentle upward curve at the end, not so strong 

 as in Dasypogon. 



