DESCRIPTION OP THE SPECIES. 227 



nab. Hayti (caught on shipboard, by Mr. P. R. Uhler, sixty 

 miles northwest of St. Nicholas, Hayti). 



Observation 1. The Trypeta described by Wiedemann as 

 Dacus serpentinus, differs from T. tricincta not only in the 

 picture of the wings, but also in the coloring. Wiedemann's 

 original specimen, compared by me, comes from Brazil ; but I 

 have received a number of specimens of the same species from 

 Peru. The Urophora vittithorax Macq. Dipt. Exot. Suppl. IV, 

 p. 286, Tab. XXVI, f. 11, is identical with T. serpentina Wied. 

 The habitat "de 1'Inde," given by Macquart, is certainly errone- 

 ous, if it means the East Indies ; but the species may occur in 

 the West Indies, just as T. fraterculus occurs in Peru, Brazil, 

 and Cuba. 



Observation 2. T. suspensa Lw., fraterculus Wied., ludens 

 n. sp., and tricincta n. sp., and a considerable number of other 

 American species, among which T. serpentina Wied. and obliqua 

 Macq., have already been mentioned above, form a well-defined 

 group, which well deserves to be considered as a separate genus. 

 The character which distinguishes it from all other Trypetina, is 

 the course of the fourth longitudinal vein, which, towards its end, 

 is curved forwards in a rather striking manner, and reaches 

 the margin at a very acute angle, being prolonged beyond as 

 the costal vein. With reference to this character I propose to 

 call it Acrotoxa. The species of this group have, moreover, the 

 following characters in common : In the structure of the head and 

 of all its parts they resemble the species of Hexachseta; the 

 thorax has a similar structure, but it is a little smaller in bulk, as 

 compared to the rest of the body, and a little narrower between 

 the roots of the wings ; the macrochffltae of the thoracic dorsum 

 agree with those of Hexachseta both in their number and position. 

 The scutellum is smaller than in the latter genus and not quite 

 as flat, and bears not six, but four macrochffitae. Front femora 

 on the upper side with shorter, on the under side with longer 

 bristles and the front tibia? without bristles, as in the species of 

 Hexachseta. Middle femora without bristles ; only the basis of 

 the under side is sometimes provided with one or several bristle- 

 like hairs ; the two rows of bristles which, in Hexachseta, are 

 found on the under side of the middle femora, are replaced here 

 by two rows of hairs. Middle tibia? without bristles. Hind 

 femora towards the end of their upper side, more or less densely 



