INTRODUCTION 



ROBBER FLIES OF THE WORLD 



23 



prosopis Macquart, James (1939) has commented on 

 venational differences in his species Ceraturgopsis 

 praecursor James. 



Genera Known Only From Fossil 



The following genera are known only from fossils: 



Genus Stenocinclis Scudder 



Figure 2536 



Stenocinclis Scudder, Rep. U.S. Geol. Surv. Terr., vol. 13, p. 

 563, 1890. Type of genus : Stenocinclis anomala Scudder, 

 1890, by monotypy. 



I quote Scudder's description : 



This genus is founded wholly upon characters drawn from 

 the neuration of the wings, the only portion of the insect 

 preserved. It falls into the group of Dasypogonina, in which 

 the second longitudinal vein terminates on the margin apart 

 from the first longitudinal vein instead of uniting with it just 

 before the margin. It is not very far removed from Dioctria 

 Meigen but differs from it and all Asilids I have examined in 

 that the third longitudinal vein arises from the first before 

 the middle of the wing, instead of from the second longitudinal 

 vein after its emission from the first ; the first longitudinal 

 vein has therefore 2 inferior shoots, giving the wing a very 

 peculiar aspect ; indeed it would be hard to know where to 

 look for a similar feature among allied Diptera unless it would 

 be in the anomalous group of Cyrtidae. The wing is very 

 slender and all the cells unusually elongated which also gives 

 it a very unique appearance. 



In the figure the curve of the presumptive anterior 

 branch of third vein is similar to any one of several 

 genera, as for example, Saropogon Loew, Laphystia 

 Loew, Dioctria Meigen. 



Genus Asilopsis Cockerell 



Figure 2535 



Asilopsis Cockerell, Proc. U.S. Nat. Mus., vol. 57, pp. 250-251, 

 1920. Type of genus: Asilopsis fuscultis Cockerell, 1920, 

 by original designation. 



I quote from Cockerell's descriptions of Asilopsis 

 and A. fusoulus, as follows : 



Small flies apparently related to Asilinae or Laphriinae; 

 marginal cell closed far from end of wing; base of marginal 

 obtuse, and the part basad of basal end of first submarginal 

 much longer than that apicad of it; first basal on first sub- 

 marginal scarcely longer than anterior cross-vein ; diseal cell 

 elongated, with anterior cross-vein far toward the base; two 

 submarginal cells, the second less than half as long as the 

 first; second posterior cell somewhat swollen towards base; 

 fourth posterior apparently open. . . . The dark cloud in the 

 apical part of the marginal cell is suggestive of Leptidae, and 

 is not an asilid character. It is possible if we had the whole 

 fly a distinct family would be indicated, and on the wing 

 alone it seems justifiable to establish a subfamily Asilopsinae. 



Cockerell calls attention to a dark cloud at the end 

 of the marginal cell, speaking of it as a leptid char- 

 acter. Cockerell's whole genus is based upon a wing 

 only, and I should like to point out that a dark, stigmal 

 spot near or associated with the apex of the marginal 

 cell is also characteristic of some stratiomyids, as Al- 

 lognosta Osten Sacken and Beris Latreille. Since the 



535914— 62— pt. 1 3 



first and second veins end so close together in Xylopha- 

 gus Meigen, it would not require any great change to 

 derive from it a wing very similar to Asilopsis Cock- 

 erell. Apart from the peculiar, marginal cell the vena- 

 tion is a great deal like some species of Cyrtopogon 

 Loew and Toremyia Hull. Since it is possible to pick 

 out rhagionid wings not too far removed from asilid 

 wings, the ultimate interpretation of Asilopsis Cock- 

 erell must rest upon the presence or absence of a pro- 

 boscis and the character of the pretarsus. Without 

 further material and for the reasons given above, I 

 reject a subfamily based upon this fly. 



Subgenus Eosenoprosopis Hull 



Eoscnoprosopis Hull, Psyche, vol. 64, no. 2, p. 42, 1957. Type 

 of subgenus : Senoprosopis romeri Hull, 1957, by original 

 designation. 



Wing with no posterior crossvein, the veins at end 

 of second basal cell crossed and the fourth posterior 

 cell with no petiole at its base. Anterior branch of 

 third vein ends clearly at the apex of the wing, as in 

 Opopotes Hull, a Recent genus. It appears to be in- 

 termediate between Opopotes and Senoprosopis Mac- 

 quart. 



I wish also to comment upon the assignment of Seno- 

 basis antiqua James, since I have examined the type. 

 In the type the preservation of the apex of the right 

 fore tibia is excellent; it shows a weak spine or tibial 

 process with no basitarsal modification and is in very 

 much contrast to the pronounced and remarkable pro- 

 tuberance present in all species of Senobasis Macquart 

 today with their accompanying flangelike process of the 

 basitarsus. I consider it more likely that the fly in 

 question is related to Lestomyia Williston. I therefore 

 propose for Senobasis antiqua the new genus Palaeomo- 

 lobra with type of genus antiqua James. 



Palaeomolobra, new genus 



Type of genus : Senobasis antiqua James, 1939. 



This genus is defined by the weak spine on anterior 

 tibia, the widely open marginal cell and the closed 

 fourth posterior cell with the posterior intercalary vein 

 strongly convex. 



Checklist of Fossil Asilids 



The list below gives by subfamily the known species 

 and genera of fossil asilids and is believed to be com- 

 plete as of 1953. Eeferences are included in the gen- 

 eral bibliography. 



FROM EOCENE FORMATIONS 



Dastpogoninae 



Stenocinclis anomala Scudder, 1890. Green River shales. 



Asilinae 



Asilopsis fusculus Cockerell, 1920. Green River shales. 

 Asilus palacolestes Cockerell, 1921. Green River shales. 



