comparative Chcstotaxy, 499 



with tlie full benefit of a long experience. It was a 

 deliberate attempt (as Loew says in the introduction to 

 it) to act as an arbiter between the conflicting terminolo- 

 gies of previous writers, and for this reason it deserves 

 the highest consideration. In the nomenclature of 

 bristles I have taken into account the terms introduced 

 by earlier writers, as far as consistency permitted it. 



Sufficient attention has not yet been paid to the func- 

 tions of the macrochtetse in Diptera, and to the remark- 

 able circumstance that, while they occur with great 

 regularity through a long series of families, they are 

 wanting in others. 



Among the Orthorhapha the Diptera eremochseta (bris- 

 tleless) form the rule, the cheetophora the exception ; 

 but this exception comprises the large and important 

 families of AsilicUe and Doliclwpodidce. (The bristles on 

 the legs of the MycetopliiUdce and Culicidce are not 

 properly macrochaetae). 



Among the Cyclorhapha the Diptera ch^tophora are 

 the rule ; the eremochseta form the exception, but a very 

 important one — the large family of SyrpJtida. 



Macquart thought that the macrochsetse serve as a 

 protection to the parts of the body upon which they are 

 inserted ; that they act as buffers in cases of sudden 

 contact. In the Introduction to his 'Nouvelles Observa- 

 tions sur les Tachinaires' (Ann. Soc. Entom. Fr., 1845, 

 pp. 239 — 240) he says : — "En examinant la situation et 

 la direction de ces soies, qui sont d'ailleurs les memes 

 dans la plupart des Muscides, il est impossible d'en 

 meconnaatre la destination. Elles protegent toutes les 

 parties superieures de la tete centre les chocs, et Ton ne 

 pent guere douter que ces moyens de preservation n'aient 

 ete accordes a cette famille immense, a I'exclusion de la 

 generalite des autres Dij)teres, pour compenser la faiblesse 

 des tegumens. Les quatre soies occipitales, en se di- 

 rigeant en arriere, defendent le cou ; les deux stemma- 

 tiques, tournees en avant, previennent les dangers aux- 

 quelles les ocelles sont exposes, surtout pendant le vol ; 

 les laterales du rang interieur, dirigees en dedans, forment 

 une voute pour abriter le crane qui recouvre le cerveau ; 

 enfin, celles du rang inferieur dans les femelles, tournees 

 en avant, defendent les cotes du front, elargis dans ce 

 sexe." Macquart might have continued in the same 

 strain about the bristles of the thorax ; the supra-alar 

 bristles protect the root of the wings from above; the 



