[Berliner entoniolog. Zeitschrift Bd. XXVII. 1883. Heft IL] 295 



Synonymica concerning exotic dipterology. No. IL 



C. R. Osten Sacken. 



A first instalment of these Synonymica was published by me iii 

 the Wiener Entomol. Zeitschr. 1882, p. 19 — 21. I deem it useful to 

 continue their publication from time to time, although I hope, by and 

 by, to incorporate them all in a general catalogue of the described 

 exotic diptera. This catalogue is already prepared in manuscript, but 

 requires some revision. The Nemocera I hope to publish soon. 



I. Dialysis Walker, Ins. Saund. p. 4 (0. Sacken, Catal. N. Am. 

 Dipt. p. 43). This genus is the same as Triptotricha Loew. (Leptidae). 



During my earlier visits to the Brit. Mus. I have not been able 

 to find this genus among the collections. This summer (1883) I noticed 

 3 specimen wrongly labeled Xylophagus americanus Wied. which is 

 a Triptotricha, and which, I have no doubt, is the type of Mr. Walker's 

 Dialysis dissimilis, Mr. Walker introduced this specimen in the 

 Catal. Dipt. Br. Mus. I, p. 128 as Xyl. americanus Wied. with a query, 

 und the remark that ,,it does not quite agree with Mr. Wiedemann's 

 description." This disagreement was very natural, considering that the 

 specimen is a Leptid and Mr. W.'s Xyl. americanus a Subula. Later, 

 in the Dipt. Saund. Mr. Walker described this same specimen as 

 Dialysis dissimilis nov. gen. et spec , which he still considered a 

 Xylophagid (!). As ä synonym is added: Xyl. americanus? Cat. Dipt. 

 B. M. I, 128. At the same time he left the old label to the specimen, 

 apparently forgetting to ädd a new one, and thus arose the difficulty 

 in discovering the type-specimen. As Mr. Walker's definition of Dialysis 

 does not contain any of the characteristic marks of Triptotricha, and, 

 on the contrary, as it is vitiated by a misleading datum in being placed 

 among the Xylophagidae, it cannot be considered a definition at all, 

 and Dialysis ought not to supersede Triptotricha. 



In the Ann. Soc. Entom. Fr. 1879, p. 197, Mr. Bigot described 

 a Dialysis dispar from Cahfornia, which he also refers to the Xylo- 

 phagidae. This is likewise a Triptrotricha, a fact which the author's 

 kindness enabled me to ascertain in bis own coUection. 



