290 Mr. Westwoop on Diopsis, 
Of the history of this genus few words will suffice. Linnzeus in 1775 esta- 
blished the genus, and described one species only, D. ichneumonea, which name 
Fabricius adopted ; but it would appear that the latter confounded, under that 
name, two species distinct from each other as well as from the original species. 
Illiger added another species, D. nigra; Donovan also described another from 
the East Indies under the name of D. ichneumonea ; Say added a North Ame- 
rican species, D. brevicornis; and Dalman, three new African species, noticing 
also Linnzeus’s and Illiger's species, and the confusion in the specific description 
of Fabricius, but overlooking Donovan's error. Wiedemann followed Dalman, 
adding another species, D. Dalmanni, and giving the Fabrician species as distinct 
under the name of D. confusa, making (together with Say's insect) 8 species ; 
to which Mr. G. R. Gray has added another in Griffith's Animal Kingdom. In 
the following pages 18 species, together with 3 doubtful ones, are described *. 
As in Paussus, the geographical range of Diopsis seems confined to the tro- 
pical climates of the Old World; the central parts of Africa (to which alone 
Dalman thought it restricted), the East Indies and Indian islands producing 
all the species, except Say’s North American one, which scarcely seems to 
belong to the genus. 
As to the affinities of the genus, Linnzus, from the existence of its halteres 
and small proboscis, was convinced that it was a Dipterous insect, although in 
its spinose thorax it differed very much from all the Diptera, approaching 
Formica, whilst in its long legs, clavate abdomen, and spotted wings it re- 
sembled the Ichneumons. 
Latreille was very early aware of its affinity with the domestic fly, and he 
accordingly placed it in the great group Muscidae, in the same division with 
the genera Sepedon, Tetanocera, Oscinis, Calobata, and Achias (Gen. Crust. &c., 
vol. iv.). Fallen, who divided the Muscide into four subfamilies, placed Di- 
opsis amongst the Ortalides, including Sepedon, Tephritis, Sepsis, Micropeza, &c. 
Dalman, however, from its short rounded antenne, deemed it to belong to Fal- 
len's Micromyzida, adding, * Melius forsan ad propriam familiam Diopsis cum 
Achia amandanda.” Wiedemann, however, in his memoir upon Achias, ex- 
* [ have not been able to discover in our public libraries a copy of MM. Villars and Capelle's 
Journal de la Société de Santé et d' Histoire Naturelle de Bordeauz, in the first volume of which (p. 77.), 
I believe Latreille published a notice or memoir upon this genus. 
