EHAOHICEEUS. 63 



antennae. Antennas pectinate; the length of the branches of the joints gradually 

 diminishing towards the tip ; the longest branch, that on the first joint of the 

 flagellum, equal in length to 5 or 6 joints (the number of joints cannot be stated, 

 as the tips of both antennae are broken off at the same place ; it must be over thirty ; 

 28 joints of each antenna are remaining). The posterior margins of the three inter- 

 mediate abdominal segments are fringed with white hairs. Coxae and femora black, 

 shining ; the four anterior tibiae and the base of the tarsi have a pale ground-colour, 

 darkened by a dense microscopic appressed pubescence, the rest of the tarsi black ; hind 

 tibiae and tarsi black, the former with a white ring at the base, occupying about one 

 third of their length. Wings black, darker towards the anterior margin ana! the base ; 

 subhyaline streaks in the middle of the marginal, second basal, anal, third, fourth, and 

 fifth posterior cells ; the streak on the latter is triangular in shape ; venation like the 

 other species of the genus ; fourth posterior cell and anal cell closed ; anterior cross-vein 

 at about the middle of the distance between the tip of the praefurca and the bifurcation 

 of the third vein. A single female specimen. 



N.B. — This is the eleventh species described of this remarkable genus. It has 

 the excision of the inner orbit of the eye, the short basal joints of the antennae, and the 

 other characteristic marks of Bhachicerus. I regret not to have any of the other species 

 at hand for comparison. 



Besides this, the only species of Xylophagidae described from Mexico or Central 

 America is : — 



Bhachicerus nigripalpus, Loew, Berl. ent. Zeit. 1874, p. 378. — Mexico. 



N.B. — In the Berl. ent. Zeit. 1882, pp. 364-366, I have expressed my doubts about 

 the constitution of the family Xylophagidae, and said that after the elimination of the 

 forms foreign to it, the genus Xylophagus would have to be brought into closer connec- 

 tion with the Leptidae. I still hold this opinion, although I am not prepared to give 

 it an immediate practical application. 



Fam. ACAffTHOMEKIDJE. 



Although a good many species of this family have been described, very little has been 

 done in the way of generalizing the characters of the family and of the two genera now 

 composing it — Acanthomera and Bhaphiorhynchus. 



This is so far true that even the sexual characters have not been clearly defined ; 

 in several cases the sexes of the same species have been described under different 

 names, and even placed in different genera. 



The sexes in this family, as in many other families of Diptera, are easily distin- 

 guishable by the contiguity or non-contiguity of the eyes and by the shape of the 

 abdomen. The difference in the structure of the antennae has never been distinctly 



