Characteristik der Gattungen der N otacanthen. 365 



are remarkably alike; the difference consists in the double commissures 

 connecting the nervous knots in Leptis, a difference certainly less 

 important tlian the above mentioned resemblance. 



II. My other objection against Dr. Loew's conception of the family 

 Xylophagidae refers to the location in it of the genus Arthropeas. 

 In the notes to my Catal. N.-Am. Dipt. 1878 (page 223) an insect is 

 described which I referred provisionally to the genus Arthropeas. It 

 has the body of a Leptid (Symphoromyia), with the antennae of a 

 Coenomyia. It will probably form a new genus, because besides the 

 differences in the venation noticed by me in the deseription, it has no 

 spurs on the front tibiae, while such spurs are distinct in Arthrop- 

 sibirica. *) There can be no doubt of the relationship of that species 

 to Arthropeas on on side, and of its belonging to the Leptid ae on the 

 other. A different species (from Washington Territory), apparently of 

 the same genus, was recently communicated to me by Dr. Willis ton 

 in New Haven; unfortunately it reached me in fragments. — The genus 

 Cflutops belongs in the same group, and as it was discovered during 

 the preparation of my Catalogue, I feit at liberty to dispose of it, and 

 laid Claim by means of it to the position of the whole group among 

 the Leptidae. (See Note II). 



To sum up: of the components of Loew's Xylophagidae, Subtda 

 aloue, in my opinion, must remain among the Notacantha. It may be 

 placed among the Beridina, until its relationship is cleared up. Ar- 

 thropeas, Ghitops and my nov. gen. must be connected with the Lep- 

 tidae. JCylophagus and Coenomyia would form the stock of the 

 reformed family Xylophagidae, which must be brought in nearer connection 

 with the Leptidae, and not with the Notacantha. 



When I said above, that routine, and nothing eise, seems to have 

 kept Subula and Xylophagus united in the same ultimate subdivision, 

 I should have excepted two authors : Latreille and Westwood. 



In judging of Latreille's conception of the Notacantha, authors seem 

 to have overlooked a rather important circumstance: Xylophagus, in 

 Latreille's meaning, is equivalent to our Subula only. Our 

 Xylophagus is his Pachystomus. (See Note III). As soon as we 

 examine his System in the light of this Interpretation, we find that it 

 agrees with the distribution which I am proposing, and that my re- 

 formed Xylophagidae, that is the Xylophagidae minus Subula, are 



^) I obtained this and other details on Arthropeas sibirica through 

 the kindness of Dr. Karsch in Berlin; his data confirm me in the 

 belief that Arthropeas must be referred to the Leptidae. 



24* 



