150 MK. E. SHELFORD ON A NEW GENUS OF DIPTERA. 



^Ni&MATisTES AFJticANus, B. new Genus and Species of Diptera. 

 By K. Shelford, M.A., F.L.S. 



(Plate 22.) 



[Read 7th November, 1907.] 



Quite recently, Professor E. L. Bouvier of the Museum d'Histoire Naturelle, 

 Paris, entrusted to me for examination a minute insect from British East 

 Africa, bearing a superficial resemblance to a cockroach. The unique 

 specimen was gummed on to a piece of card, so that little could be made out 

 of its external anatomy when examined with a simple pocket-lens ; however, 

 when the specimen had been soaked off the card and placed under a micro- 

 scope, it was at once seen that it had no affinities with the Orthoptera. I am 

 indebted to Dr. H. J. Hansen of Copenhagen, whom I was fortunate enough 

 to meet in London, for giving me a clue to the real nature of the insect. 

 There can be little doubt that the insect's nearest known ally is ^nigmatias 

 hlattoides, an aberrant Phorid fly described by Meinert from Denmark [1*] 

 in 1890 ; but the relationship, as might be expected from the very different 

 localities of the two insects, is not at all close, in fact the differences between 

 them are almost as striking as the resemblances. The following is a 

 description of the new genus : — 



jEnigmatistes t, gen. nov. 



Mead prominent, subpyramidal ; the morphologically anterior part lies in 

 a plane almost at right angles to the plane of the posterior part and the 

 middle region of the frons is produced and sharply ridged, making the 

 angulation more pronounced. The head when viewed from above is concave 

 and the vertex projects above the level of the pronotum. The frons im- 

 mediately below the ridge is slightly concave, but then becomes strongly 

 convex. On either side of the head is situated a deep depression in which lies 

 the antenna. 



The eyes have few facets, are somewhat pyriform in outline, and are placed 

 laterally at the postero-ventral angles of the head (PI. 22. fig. 3). A stout 

 seta, upwardly curved, springs from a point just below each eye. Ocelli 

 absent. 



The antennce (PI. 22. fig. 4) are composed of 7 visible joints. The first 

 is large, swollen and trapezoidal, the third is large and globular ; the second 

 is a connecting joint between the first and third and in surface view appears 

 to be short and slender, in optical section it appears to expand within the 



* These numbers refer to the BibUography at the end of this paper, 

 t diPiyixaTLo-TTjs, one that propounds riddles. 



