8 
a large part of Mr. Hamm’s time has been the double labelling, 
with names and localities, of the fine collection of British 
Diptera presented—worked out and complete—by Colonel 
J. W. Yerbury, F.Z.S., as well as the beautifully prepared speci- 
mens given by Mr. F. C. Adams, and the smaller collections 
presented by Mr. Hamm himself, Mr. Holland, and Dr. Jenkin- 
son, D.Litt. Colonel Yerbury has also on many occasions 
assisted us by the determination of the species in these latter 
collections. Here in the University it is of the utmost im- 
portance to pay special attention to the British collections, 
and our gratitude is correspondingly deep when we receive 
so much kind help in material and in time and study as 
Colonel Yerbury has generously given us. 
In speaking of the numerous researches which have been 
carried on in the Department or upon its material, the first 
place must be accorded to Dr. F. A. Dixey’s ten years’ work 
upon the Pzerzxae—the large group of butterflies represented 
in this country by the familiar “ Whites,” “ Clouded Yellows,” 
“ Orange-tip,’ and “ Brimstone.” This great labour on behalf 
of learning and of the University reached its completion in 
the summer of 1903. The following brief account of the 
results attained has been kindly furnished by Dr. Dixey 
himself :— 
“In 1893 the Pierinae in the Hope Collection occupied 
about 50 drawers; they were to some extent sorted out into 
genera and species, but the arrangement did not pretend to 
critical exactness, nor did it profess to represent the existing 
knowledge of the different species with their distribution and 
affinities. There were no labels except those in MS. attached 
to the individual specimens. These were often elaborate and 
written with much care; but they could not as a rule be read 
without removal of the specimen from the cabinet. The 
greater number of the species were grouped together, but 
several were detached from the general arrangement, and had 
to be sought in different parts of the collection. For reasons 
of this kind the difficulties in the way of making an effective 
study of the group were very great. 
