332 



PSYCHE. 



('October 1S02. 



uated on the edges of the vibrissal 

 ridges, and the long one on the vibris- 

 sal angle are called vibrissae. If the 

 ridges bear such bristles up to above 

 the middle, the term "vibrissae ascend- 

 ing" is used to describe the character. 

 If they are in a single row, they are 

 simple or one-rowed ; if in two or moi - e, 

 they are double rowed or bushy. Bris- 

 tles on the edge of the cheeks (sides of 

 face) may be mistaken for ascending 

 vibrissae, but check vibrissae are al- 

 ways below the vibrissal angle. . . . 



In relation to wing structure, we 

 adopt in general the terminology used 

 by Meigen, aud therefore differ from 

 Rondani in the names of the veins. 



The larger bristles on the abdomen 

 we (with Rondani and Macquart) call 

 macrochaetae ; those on the posterior 

 margin of the segment marginal, and 

 those on the surface of the dorsal line 

 discal. If these bristles stand at the 

 side of the body, they are lateral. 

 When we speak distinctly of discal and 

 marginal macrochaetae, we always 

 mean those in the dorsal (sagittal) line. 

 If a further distinction is necessary, 

 the bristles of the posterior edge may 

 be distinguished as of the whole mar- 

 gin, or discal, or lateral ; or, if in the 

 middle only, as sagittal. Some tropi- 

 cal forms show particularly large bris- 

 tles which are thick and straight, like 

 spines, and often cover the whole ab- 

 domen, or stand together in groups, 

 dusn-like. Van der Wulp distinguishes 

 these spines in certain groups, and we 

 follow him in this respect in the dis- 

 tinction of narrow groups. But they 

 form no character of a particular group 

 Vvit occur in several, which are sepa- 



rated from each other by other struct- 

 ures. All the remaining terms should 

 be intelligible, as we follow entirely the 

 methods of expression of Loew, Schiner, 

 etc. 



In regard to generic names, it has 

 been our intention to retain the old 

 name for that part of the genus to which 

 the oldest species belongs. If that is 

 impossible, on account of the name 

 having been proposed for several species 

 which now belong to other genera, the 

 name must either be used in a narrower 

 sense or discarded, because in the re- 

 tention of names which had one mean- 

 ing originally, and another quite 

 different one now, only confusion and 

 misunderstanding can arise. It is de- 

 sirable also that describers of new species 

 should not enlarge or narrow our genera 

 as soon as species are found not exactly 

 corresponding with their characters, 

 but rather that they erect new genera, 

 for the very good reason that, after this 

 kind of modification by little patches 

 has gone on for a time, it will be impos- 

 sible to characterize the genus. . . . 



The majority of authors seem never 

 to have troubled themselves to give any 

 account of the ideas represented by 

 Tachininae, Dexinae, Phasinae, etc., 

 but in all these cases to have had only 

 one definite form in mind, so that the 

 characters belonging to the name long 

 since ceased to have any weight, when 

 the habitus of the form under consider- 

 ation suggested these groups. But how 

 a different appearance may conceal re- 

 lationship, and how similiarity with un- 

 related forms may deceive, no genus 

 ever illustrated so strikingly as Sceno- 

 p/mts. 



