REVIEWS. 
77 
by Dr. Packard which has recently appeared. It is a most important con - 
tribution to entomological literature and at the same time is precisely one 
of those works which could never have been so well produced by private 
enterprise. 
The geometrid moths, the phalcence geometrce of Linnjeus, have received 
their name, as is well known to entomologists, from the peculiar mode of pro- 
gression of their caterpillars, which is a necessary consequence of their usual 
conformation. These curious larvte generally have only two pairs of fleshy 
prolegs situated close to the hinder extremity of the body, and in walking most 
of them adhere to their support alternately by these and the six true legs 
which are on the first three body segments, and thus move by a series of steps 
in which the body is alternately stretched to its full extent, and bent into a 
loop. Hence these larvae are often called loopers, a name which, among 
collectors, is sometimes applied to the moths. Another result of the 
arrangement of the prolegs so far back on the body, is that many of these 
larvae are able to mimic the twigs of the tree on which they feed in the most 
perfect manner ; clinging with the hind feet they extend their bodies stiffly 
and thus present exactly the appearance of a bare twig. 
The moths produced from these curious caterpillars are often of great 
beauty, although many of them display sober brown tints, more or less varie- 
gated. Others, although of sober colours, are adorned by having these 
arranged in most elegant patterns. But the striking species are not very 
numerous, and in general thePhalaenidae share the common lot of moths, in 
being rather difficult to determine* specifically. Staudinger and Wocke’3 
catalogue gives about 800 species of Phalsenidse as inhabitants of Europe, 
and although in the present work Dr. Packard does not describe half this 
number, those who have ever laboured at the discrimination and determina- 
tion of species of moths will know that he must have undergone very 
considerable labour in preparing his monograph. 
But whatever labour it may have cost him he may certainly congratulate 
himself on having produced a work which will be received with gratitude 
by all students of American Lepidoptera both at home and abroad. All the 
known species and varieties are described in detail, both the generic and 
specific synonymy is given in full and with dates, a most important matter 
in a work of this description, and all the species are figured. To make 
his treatise more complete, Dr. Packard has also quoted under the title 
u Desiderata,” the original descriptions of the species which he has been 
unable to see, thus enabling any entomologist who may meet with one of 
them to determine the nature of his prize. In defining his genera Dr. 
Packard has availed himself largely of the characters derived from the 
venation of the wings, which have long been regarded as of great import- 
ance in the study of the Hymenoptera and Diptera, but have only of late years 
been much employed among Lepidoptera. Unfortunately the use of such 
characters is liable to be pushed too far, and even in the present excellent 
work we recognise the tendency to excessive generic division which is the 
great vice of systematic zoologists of the present day. However, Dr. 
Packard has certainly done his best to render matters as plain as possible, 
for he furnishes the student with six plates containing figures of the vena- 
tion of the wings of all his genera. Besides, there is a plate of outlines of 
