August, 1905. 1 ]^73 



ON THE TERMINOLOGY OP THE LEG-BRISTLES OF DIPTERA. 

 BY PEUCY H. GBIMSIIAW, P.E.S. 



For .some little time I have felt the necessity for a definite system 

 of names for the bristles on the legs of flies, and this need became 

 more prorounced when a few months ago I commenced to prepare 

 descriptions of the British species of Hydrotcea, a task which, I am 

 happy to say, is now nearly completed. Upon comparing the de- 

 scriptions of various authors it will be found that there does not 

 exist at j)resent aiiy uniform nomenclature for the bristles and hairs 

 which are attached lo the various surfaces, and in some cases the 

 terms used are somewhat ambiguous, and, certainly to my mind, un- 

 satisfactory. In certain Families of iJipicra, such as for example the 

 Anthomijiidce, these bristles are remarkably constant in arrangement, 

 and in many cases, esj)ecially where the female sex is concerned, offer 

 the safest, and sometimes almost the only, characters by which a 

 species may be recogin'sed. It therefore seems to me highly desirable 

 that some uniform system should be adopted whereby the chsetotaxy 

 and pubescence of the legs may be described, so that the rows of 

 bristles or even individual hairs may be at once recognised and 

 differentiated. 



In order to emphasize the want of uniformity above alluded to, I 

 quote a few examples, and in doing so must explain, that I do not 

 bring them forward in any spirit of carping criticism, but merely for 

 the purpose I have stated, and to serve as my apology for introducing 

 the system of names which follows. (1). Stein, in his valuable 

 paper on the European species of Hydrotcea (Verb, zool.-bot. Ges. 

 Wien, 1903, pp. 285-337) says, in his Latin diagnosis of H. similis, 

 "tibiis posticis intus in latere a corpore averso 5-6 setia instructis," 

 and further, in his German description, says '' Die Hinterschienen 

 sind aussen abgewandt mit kurzen Bor.stchen bewimpert . . innen 

 abgewandt sind sie fast der ganzen Lange nach mit kriiftigen Borsten 

 versehen." (2). Meade, in describing the same species (Ent. Mo. 

 Mag., vol. xxiii, p. 251) says " the hind tibiae . . . differ from 

 those of II. dentipes by having a group of strong bristles in the 

 middle of their anterior or under surfaces." (3). The same author, 

 in his paper on the British species of Sarcophaga (Ent. Mo. Mag., 

 vol. xii, 1875-0) speaks of the beard on the inner side of the hind 

 tibiae of the male. (4). Hough, in his description of a new species 

 of Faracompsomyia (Proc. Acad. Nat. Sci. Philadelphia, 1898, p. 186) 

 describes the bristles of the tibiae as follows : — " anterior tibia has on 



