INSECTA. 
333 
In this memoir Walsh discusses certain statements, chiefly 
made by Professor Agassiz, upon questions relating to general 
entomology. I. Agassiz has made the rather incautious asser- 
tion, in liis hook on Lake Superior, that the insects of the tem- 
perate zone of North America differ specifically throughout 
from those of Europe. Walsh indicates that this statement is 
negatived even by Leconte^s catalogue of insects, published in the 
above-mentioned work, which contains several species regarded 
as common to both continents. In further support of the iden- 
tity of many European and North American species, Walsh has 
prepared a list systematically arranged (p. 211 et seq.), which 
shows no fewer than 304 species regarded as identical with 
European forms, the majority belonging to the orders Coleo- 
ptera (50), Lepidoptera (57), and Diptera (165). Besides these 
there are 56 species so nearly allied to European forms that 
their distinctness is very doubtful. Starting from these facts, 
Walsh discusses the distribution of insects in North America in 
opposition to the views of Agassiz, and in sup{)ort of the Dar- 
winian theory. II. The second section of the paper is devoted 
to a discussion of the Darwinian theory of the origin of species; 
and in it Walsh endeavours to show that Agassiz has never 
carefully read DarwirEs book, and certainly proves that if he 
did read it he did not understand it, and that in his work on 
^ Methods of Study ^ Darwin’s views are completely misstated. 
This section contains some remarks on variation in several spe- 
cies of insects. III. In the third section Walsh considers the 
assertion of Agassiz, that all insects pass through a worm-like 
larva stage, and maintains that in those cases where the em- 
bryo of an insect with imperfect metamorphosis seems to pass 
through a worm-like stage in the egg, this is not homologous 
with the worm-like larval state of the Lepidoptera, Diptera, 
&c. Walsh regards this as a vague analogy, and applies the 
same term with equal justice, in his Section IV., to the fanciful 
resemblances traced by Agassiz between the pupae of insects 
and the Crustacea. V. In a fifth section the author urges the 
phenomena of retrograde metamorphosis in opposition to the 
assertion of Agassiz that " the earliest condition of an animal 
cannot be its highest condition,” and indicates that the deter- 
mination of the relative superiority of the different orders of 
insects cannot be arrived at by the consideration of any one 
character, but by a review of all the characters of each order. 
Section VI. is devoted to a consideration of Dana’s system of 
insects, founded on what he calls the principle of cephalization, 
and to an indication of many of the defects of that fanciful 
arrangement; and Section VII. to an exposition of several erro- 
neous statements and generalizations made by Dana in his paper 
on Classification. 
