374 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



raarginal cell forming a cross or X, R, proceeding from the apical point 

 of the cell; veins apically limiting basal cells oblique, in a straight Ime 

 with one another, exactly as in M. niveitarsis Alexander. The follow- 

 ing measurements are in microns: length of first marginal cell, 1950; 

 first basal on submarginal, 400; apical side of first basal, 224; apical 

 side of second basal, 320; first marginal on first submarginal, 800. 



Oligocene: Gurnet Bay (Brodie). British Museum, I. 8635. The 

 X at end of first marginal cell is distinctive. The position of Rj shifts 

 in various members of the genus. In M. pallida WiUiston and M. 

 fragillima Westwood it separates considerably beyond the end of first 

 marginal cell, but in M. niveitarsis it is before (basad of) the tip of that 

 cell, or rather originates from the upper corner of the truncate tip. 

 The genus Mongoma is today tropicopolitan, and on account of the 

 diversity of venation has been divided by authors, but Alexander 

 shows that the groups grade into one another. 



TIPULA GABDNERI, new species (Tipulidae). 



Plate 31, fig. 1. 



Wing about 18 mm. long and 4 wide, the apex low down, giving the 

 wing a subfalcate appearance; no distinct markings but a dark gray 

 stigmatic cloud, the end of which is 5 mm. from apex of wing; second 

 vein (R2+3) not evidently turned upward at end; third vein going to 

 wing tip; costal vein bounding marginal and submarginal cells very 

 strong and dark ; discal cell rather long and narrow, as in some of the 

 American Miocene (Florissant) species; fifth posterior not quit€ 

 touching discal. 



Oligocene: Gurnet Bay (Brodie). British Museum, I. 8663. This 

 is readily known from the species of Baltic amber by its size. It is 

 named after J. S. Gardner, who is known for his work on the Tertiary 

 plants of England. 



BIBIO WICKHAMI Cockerel! (Bibionidae). 



A new specimen from Florissant (U.S.N.M.) has the following char- 

 actei-s: Length about 11.25 mm.; wing, nearly 7; head, thorax, and 

 legs, black; abdomen, reddish brown, with broad hyaline bands, 

 which are about half as wide as the intervals between them; wings 

 hyaline, the costal field broadly suffusedly brownish, a large dusky 

 stigmatic spot. Wing measurements in microns: Third vein 

 before anterior cross-vein, 640; third vein beyond cross-vein, 3,520; 

 cross-vein, 80; width of first posterior cell at level of end of third 

 vein, 640; width of second at same level, 608; third posterior cell on 

 wing margin, 1,280. 



