lx 
well observes that it conceals the epoch when a species was first 
made known, and it also prevents us from going direct to the 
work where we shall find the species first described. 
The body of Dr. Thorell’s work is devoted to a thorough 
examination of the literature and classification of Huropean 
spiders, with especial reference to two important Monographs, the 
authors of which were each unacquainted with the other's works. 
These are, Westring’s ‘ Aranei Suecice,’ and Blackwall’s ‘ British 
Spiders,’ which, although largely treating of the same insects 
differ widely in their nomenclature. Both works were published 
about the same time, and they exhibit a remarkable coincidence 
in the number of species inhabiting the two countries, Sweden 
having 308, Great Britain and Ireland 804. A considerable 
number of southern forms occur with us which are wanting in 
Sweden, the latter country of course possessing a corresponding 
proportion of northern and continental forms which we have not. 
The portion of the work already published is devoted to a critical 
examination of the genera, both as regards synonymy, classification 
and structural characters; the species will, I suppose, be after- 
wards treated in a similar manner. 
Of aless extensive scope is Dr. Hagen’s ‘Monograph of the 
fresh water Astacidee of North America, which, besides going 
into interesting anatomical details, brings out a curious fact in 
geographical distribution, analogous to what occurs in some 
groups of insects. These crawfishes consist of two well-marked 
genera, Cambarus and Astacus. Cambarus contains 32 species, 
and is entirely confined to North America, east of the Rocky 
Mountains. Astacus, on the other hand, is confined to the Pacific 
coast of America, but also extends into Europe and Asia. 
Another work, which may be considered a new one, is Stau- 
dinger and Wocke’s new edition of their Catalogue of European 
Lepidoptera, which is now extended to include all the species of 
the Europeo-Asiatic Fauna. ‘The limits defined are nearly, but 
not quite, the same as those of Dr. Sclater’s Palearctic region. 
They extend from Iceland to the mouth of the Amur river, going 
only as far south as 45° or 50° latitude in the east, while in the 
west of Asia there is an extension as far as 30° in South Persia. 
The south-east of Persia, towards Affghanistan, is said to show a 
transition towards the Indian Fauna. Syria and Palestine are 
wholly European, while Arabia and Egypt should probably be 
