TABANIDJE. 49 



15. ACANTHOMEEID^E. 



Very large, the largest among diptera, stout, bristleless, 

 nearly bare flies. Eyes large, contiguous in the male. Ocelli 

 present. Third joint of the antennae complex, composed of 

 seven segments, with a terminal, often in the male setiform 

 style. Proboscis short, not adapted for piercing, with fleshy 

 labella. Tegulae rudimentary. Tibiae without spurs ; pulvilli 

 and empodia pad-like. Wings with two submarginal and five 

 posterior cells, the fourth posterior cell and the anal cell closed. 



But two genera are known in this family, including alto- 

 gether only about fifteen or sixteen species, all of which are 

 inhabitants of Central and South America. The species are 

 remarkable for their extraordinary size, some reaching nearly 

 two inches in length. The species of Acanthomera are found 

 in forests, alighting on trunks of trees, according to Mr. 

 Champion; otherwise their habits, whether of the adult or 

 immature stages, are but little known. Brauer has figured 

 and described the larvae of A. Frauenfeldii. They are cylin- 

 drical, thick and short. The last segment is firmly chitinized 

 above with two series of booklets, the two projecting back- 

 wards in the middle being stout and curved; below these 

 there is a deep, transverse cleft, on the under side of which is 

 a rounded lip. 



In both Acanthomera and Rhaphiorhynchus the face may be 

 produced conically or not at all. The two genera are distin- 

 guished by the structure of the palpi, in Acanthomera slender, 

 in Tthaphwrliyncluis stout and pointed. Acanthomera may 

 have spines on the hind femora. 



16. TABANIM;. 



Head large, transverse, somewhat flattened and with the 

 occiput flat or concave. Antennae porrect, the third joint com- 

 posed of from five to eight annuli or segments. Eyes large, 

 pubescent or bare, contiguous above in the male and with the 







