752 THE AMERICAN NATURALIST. [Vor. XXXIX. 
part of zoólogy as the systematic and morphological matters that fill 
the pages of this otherwise excellent work. From a mechanical 
standpoint the book is well put together. A convenient arrangement 
of small and large type helps to give light and shade. An excellent 
index has the added convenience of indicating by the use of expo- 
nents whether a name is found in the upper or lower half of the 
page. Typographical errors are relatively few though Rabl-Rückhard 
is misspelled on page 193 and its hyphen is omitted on page 321. 
The illustrations are mostly familiar if not actually threadbare and 
for some strange reason almost all from the older Claus and Sedg- 
wick are much less satisfactorily printed than in the earlier work. 
Notwithstanding such shortcomings, the volume as a whole has very 
much for genuine commendation, though its size promises to put the 
work when completed on the shelves of the teacher rather than in 
the hands of the pupil. 
G HP, 

Aldrich’s Catalogue of North American Diptera.! — Catalogue- 
making is often a thankless task, but skillfully and conscientiously 
done, the results are of the utmost importance in all systematic work 
in biology. American entomology has been especially fortunate in 
its cataloguers of the two-winged insects. The last is Professor 
J. M. Aldrich, who has just produced a voluminous work of 680 
Pages, containing full lists and bibliographies of all known American 
Species of Diptera north of South America. The work has been a 
stupendous one, involving most of the author's available time for the 
past eight years. It is, however, far more than a mere bibliograph- 
ical catalogue of genera and species, since it contains many critical 
notes on the distribution and validity of the forms catalogued. One 
Is surprised at the amount of work that has been accomplished in the 
order since the Appearance of Baron Osten-Sacken's Catalogue in 
1878. 'The number of known species has been nearly doubled, 
Increase in the genera has been even greater, there being 1230 recog- 
nized as valid in Professor Aldrich's catalogue. 
€ beginning of a new epoch in the 
study of these insects, The writer has examined the catalogue very 
lAldrich, J. M. A Catalogue of North American Diptera (or Two-winged 
, 
flies). Smithsonian Misc. Coll., vol. 46, 680 PP-; 1905. 
