80 Proceedings of the Royal Physical Society. 
greatly assisted by the labours of his contemporary, and was enabled to 
identify and record a large number of species resting in British cabinets and 
hitherto unlabelled. | | 
After the appearance of the above three works presumably the task of 
dealing with the whole of the British Insects became too heavy for one 
author to grapple with, so that special works began to appear dealing with 
a single Order. We accordingly find, after an interval of twelve years, the 
publication of the first separate work on British Diptera, viz. :— 
4, WALKER, FRANcIS: Insecta Britannica— Diptera. London, 3  vols., 
1851-1856. 
This remains, unfortunately, the only work in the English language which 
attempts to describe the whole or greater part of the species of all the 
Families of British Two-winged Flies. Descriptions are given of 2074 species, 
while 363 additional species are mentioned as British but not described. 
Fortunately for the reputation of this work, its author (a notoriously careless 
worker) was materially assisted by A. H. Haliday, a Dublin entomologist 
whose descriptive writings were remarkable for their care and accuracy. 
Those Families which were taken in hand by Haliday were finished on his 
usual high standard, and such portions of the work still remain of considerable 
use to those students who have neither access to, nor the faculty of reading, 
the various modern monographs by continental authors. Much of Walker's 
share in these three volumes is, as usual, slip-shod, and in some of the larger 
genera (eg. Chironomus) his analytical tables are unworkable, not to say 
ludicrous. Most of the species described by Walker as new are unrecognisable 
without an examination of the type specimens, which were not marked as 
such and have apparently since been lost. Such species, therefore, as Verrall 
has remarked, are “only a burden to the list.” A saving feature of this work 
lies in the thirty plates, from the hand of J. O. Westwood, and drawn with 
his usual skill and accuracy. 
No general work of any importance appeared for neatly forty years 
after the date of Walker’s last volume. In order to fill up this blank, the 
following projected work was commenced :— 
5. THEOBALD, F. V.: An Account of British Flies (Diptera). London, 1892. 
Presumably owing to want of support this effort to produce a hand-book 
soon came to an end, only a single volume of 215 pages being ear 
dealing with half-a-dozen Families. 
After devoting over thirty years to the ie of Diptera, George Hones 
Verrall issued the long-expected pioneer volume of a great projected work 
on the Flies of Britain. The whole work was to occupy some fourteen 
