84 Proceedings of the Royal Physical Society. 
for a more thorough study of our native species. It represents the 
results of more than 20 years’ study on the part of the author, and 
indicates very clearly the state of our knowledge at the time. No 
fewer than 603 genera are recognised—a great advance on all previous 
works—while the names of 3527 species are printed, those requiring 
confirmation being either printed in italics or relegated to Parts II. 
and III., which give respectively those species which were “ originally 
described from Britain; but probably unrecognisable unless from — 
types” (195 species), and “reputed British Diptera” (843 species). 
33. VERRALL, G. H.: A second Hundred new British species of Diptera. 
Ent. Mo. Mag., xxx. pp. 76-79 and 140-146 (1894). 
34. MeabE, R. H.: British Diptera unrecorded or undescribed by English 
Authors. nt. Mo. Mag., xxxv. pp. 30-33 and 100-103 (1899). 
35. VERRALL, G. H.: List of British Diptera. 2nd Edition. Cambridge, 
1901, 47 pp. This still remains the standard List, although since its 
publication some hundreds of additional species have been discovered, 
and a large number of doubtful ones confirmed, while much progress 
has been made in classification, subdivision of old and erection of new 
genera, and so on. Verrall’s 2nd Edition is a great advance on the 
first, for, as the preface states, ‘about 300 species have been added to 
the old ‘ List,’ and about 500 names have been altered in some way or 
other, such as being confirmed as British, placed under a different 
genus, changed in synonymy, etc.” The List as it stands contains in 
Part I. the names of 665 genera and 2881 species, and of the latter 
303 are printed in italics as requiring confirmation. 
36. VERRALL, G. H.: Another Hundred new British species of Diptera. 
Lint. Mo. Mag., xvii. p. 79 (1911). Completed by J. E. Cou.in, 
op. cu. xlvilil. pp. 20-27, 56-59, 144-147, 190-197 (1912). 
387. COLLIN, J. E.: Additions and Corrections to the British List of Muscide 
Acalyptrate. Hnt. Mo. Mag., xlvi. pp. 47-48, 124-129, 169-178 (1910) ; 
xlvil. pp. 145-153, 182-187, 229-234, 253-256 (1911), This is an 
exceedingly valuable paper, correcting synonymy, adding species, and 
clearing up difficulties. It is only a foretaste, showing how much 
and yet how little we know of this section of the Diptera. 
38. CoLLin, J. E.: Thirty Additions to the List of British Diptera. Hnz. Mo. 
Mag., xlix. pp. 104-106, 130-135 (1913). et 
III. Practical Hints. 
The following papers are of a practical nature :— 
39. SLACK,——: On examining Diptera under the Microscope. Knowledge, 
vol. vi. pp. 312, 313, figg. (1884), 
