268 Bibliographical Notice. 
This structure is called the jugum, or yoke, and is found only in 
the Hepialidx and Micropterygide. The Frenate form the second 
suborder, and include the other families of Lepidoptera, in which 
the fore and hind wings have different neuration and are connected 
by a frenulum, a bristle, or bundle of bristles, or by its substitute, 
a large humeral angle of the hind wing. But it will require a more 
extensive examination of the neuration of exotic Lepidoptera before 
we can determine the exact value of these characters, which appear 
hardly sufficient by themselves to justify the division of the Lepido- 
ptera into two main groups. 
Notwithstanding the importance attached by the author to the 
neuration of insects and to the desirability of establishing a uniform 
system of nomenclature for the wing-veins, which he bases largely 
on the system adopted by Redtenbacher, he is content to refer for 
details to his essay on evolution and taxonomy. ‘This, we think, is 
a great mistake. He has adopted an elaborate system of notation 
by Roman numerals, and expresses his opinion that veins iv. and vi. 
do not exist in the Lepidoptera, Diptera, and Hymenoptera; yet he 
gives no illustration of a typical wing, nor what would have been of 
almost equal importance, a series of typical illustrations of wings of 
insects of various orders, illustrating his ideas of the homologies of 
the wing-veins. ‘There are, indeed, a great number of illustrations 
of the wings of insects, but, so far as we have noticed, all those in 
which the wing-veins are numbered belong to the very orders in 
which the typical neuration is stated by Prof. Comstock to be 
defective. Are we to infer that his system breaks down when 
applied to orders with a more complicated neuration? We do not 
think that special attention should have been called to a question 
like neuration without fuller explanations having been given in the 
book itself ; it is not enough to refer to another. 
Prof. Comstock estimates the probable number of existing species 
of animals at one million. We presume he must have been quoting 
some old estimate, in order to avoid startling his readers too much. 
At present there cannot be much less than half a million nominal 
species of insects alone on our lists ; and, although a certain propor- 
tion of these will undoubtedly prove to be synonyms, yet the most 
moderate recent computation of the actual number of existing species 
of insects fixes them at 2,000,000 ; and many of those entomologists 
who are best competent to form an opinion agree with Prof. Riley in 
regarding 10,000,000 as no exaggerated estimate. And can it be 
true that there are only three kinds of true clothes-moths in North 
America, and even these all common European pests? 
Prof. Comstock has, however, succeeded in packing an enormous 
amount of information of all kinds into the moderate compass of 
his book; nor would it be just to pass over the work of the accom- 
plished lady, of whom her husband speaks as the “‘ Junior Author,” 
and whose share in the book entitles her to a place beside her prede- 
cessors, who have done so much good work, alone or conjointly, and 
both with pen and pencil, ever since the dawn of entomology. It 
