ORTALIDSE — INTRODUCTION. 15 



diptera I am acquainted with, I look for the immediate connec- 

 tions of Rhopalomera, I find them unmistakably among the 

 South African species of the genus Cestrolus, erected by me. 

 Before all, the striking structure of the head, reminding partly 

 of some genera of Ephydrinidse, partly of the Ortalidse, is very 

 much alike in both genera; this resemblance extends to the 

 mode of pilosity of the face, the shape of the antennae, and the 

 feathery pubescence of the arista. Moreover, the small develop- 

 ment of the metanotum, the shape of the hypopygium, and the 

 structure of the last segments of the female abdomen are very 

 much alike. Now, as the genus Cestrolus, through the inter- 

 mediate steps of Prosopomyia and Physogenia, approaches 

 the family of the Sapromyzidse very closely, I do not find 

 any serious objection to placing Rhopalomera in the same 

 family. That Rhopalomera is one of the extreme genera of the 

 family cannot be doubtful ; the size of the two posterior basal 

 cells especially distinguishes it from all the other genera of 

 Sapromyzidse in a very striking manner, and connects it with 

 the Sciomyzidse ; for this reason it would be also possible, by 

 slightly modifying the definition of the boundary between those 

 two families, to place Rhopalomera among the Sciomyzidse. 

 Those who will not share either of these two views, and pre- 

 fer to place among the Ortalidse a genus which is far apart from 

 all the Diptera aciphorea in the structure of the ovipositor, may 

 locate Rhopalomera in the vicinity of Richardia, on account of 

 the bareness of the first longitudinal vein, the rounded end of 

 the posterior basal cell, and the spines on the femora. 



Thus, the following diptera, described in Wiedemann's works, 

 belong to the Ortalidce: his species of Ortalis ; all the species 

 which he brings in the genera Timia, Ulidia, Cephalia, Platy- 

 stoma, Tetanops, and Pyrgota; in his genus Dacus, the three 

 species in the first division, and Dacus succinctus and bicolor 

 in the second ; in the genus Trypeta, Trypeta ocellata, obscura, 

 picta, Jlexa, trimaculata, basilaris, cyanogasler, and scutellaris ; 

 in the genus Tetanocera, his T. bispinosa, and finally, his Cor- 

 dyl ura podagrica. 



(b.) In Robineau Desvoidy. 



I turn now, not without reluctance, to the writings of R. Des- 

 voidy. In his well-known Dssai sur les Myodaires he united 



