Diptera: Nemocera vera, N.anomala and Eremochaeta. 427 



only since the application to them of a chaetotactic character, the 

 total absence of macrochaetae. This group consists of the faniilies 

 Stratiomyidae, Tahanidae, Acanthomcridae, and Leptidae (plus 

 JCylopliagidae). Among the Orthorrhapha Brachycera it repre- 

 sents the largest agglpmeration pf bristleless forms, and deserves 

 for this reason the name par excellervce of the Section Eremochaeta. 

 Besides the chaetotactic character, these families are strongly bound 

 together by other structural pcciiliarities, which naturally separate 

 them froni the Nemocera, as well as froni the remainder of the 

 Brachycera. 1. The heads (in the male) are predominantly holoptic; 

 2. bisected eyes, with larger facets above than below (in the male) 

 are of very frequent occurrence; 3. eyes of variegated colour are 

 more common in this Section than in any other of the whole Order 

 of Diptera, principally in the Stratiomyidae and Tahanidae; 4. the 

 antennae in the group Eremochaeta are characterized by what I 

 should call a morphological restlessness; there is no other group of 

 Diptera in which the structure of the antennae varies so much, even 

 in closely related genera. These various forms offer a complete 

 transition from the thread-like antennae of some N. anomala (Khy- 

 phidae) to antennae like those of Suhnla and Jiylophagus, among 

 the Brachycera, ending in the disc-and-arista type, so common in 

 the other great division the Cyclorrhapha-Athericera. This transition 

 is effected by the joints of the proximal portion of the flagellum 

 tending to coalesce and to form a Compound Joint in various shapes, 

 while the joints of the distal portion gradually pass into the form 

 of a simple bristle. 5. There are iliree luell-developed pidvilli, 

 which is one of the most characteristic features of the Eremochaeta; 

 exceptions are rare. The legs are generally smooth, without those 

 bristles and spines that distinguish the Asilidae, and, in a lesser 

 degree, the Bomhylidae and Therevidae. 



For the final adjustment of the faniilies of the division Ere- 

 mochaeta we must wait for more material. The original arrange- 

 ment was principally based upon the common European forms ; but 

 this section, perhaps more than any other, is represented by very 

 remarkable and offen anomalous forms in the other continents, espe- 

 cially in the tropics; the anomalous forms that disturbed the old 

 arrangements came especially from Chili (Coenura, Heterostomus,) 

 and recently from North America (Agyiotomyia, a Leptid, with only 

 four posterior cells; Arthroceras, also a Leptid, but with the an- 

 tennae of Caenomyia; the singnlar genus Glutops, etc.); about 

 Australia and Africa we know almost nothing. Ccrtain it is that the 



