104 THE ENTOMOLOGIST. 
Some of the most difficult problems met with in the study of 
these genitalia are involved in the striking discovery that our 
H. nictitans consists not of two species or possibly three, as Mr. Tutt 
established a considerable time ago, though not perhaps incontes- 
tably, but actually of four very distinct species, barely capable of being 
distinguished from each other without reference to the appendages 
(there is no great difficulty in separating typical English paludis and 
nictitans). An examination of the appendages suggest, nevertheless, 
that crinanensis, the new species discovered in his researches by Mr. 
Pierce, belongs not only to a distinct species but that it should be 
placed in a separate genus. The query then presents itself, Is this a 
derivative from the nictitans-paludis-lucens forms, or is it by mimi- 
cry or some other reason approaching them from elsewhere? We 
have never quite satisfied’ ourselves, perhaps from want of proper 
enquiry, that Pierce’s species lucens is identical with nictitans var. 
lucens. At any rate, lucens, Pierce, is to be found amongst series of 
simple nzctrtans in collections, and nictitans var. lucens is very com- 
monly really nzctitans. We have a strong suspicion that nzctitans, 
Pierce, and lucens, Pierce, both have forms that are erronously 
regarded as respectively nictitans and lucens. We find no discussion 
of these questions in ‘‘ The Genitalia.” 
We miss also any discussion of the question as to Noctua thulet, 
Stgr. (conflua, Tr.?). Mr. Pierce mentions conflua as identical 
with festiva, but says nothing as to what he means by conflua, 
whether the mainland var. of festiva, or the distinct or semi-distinet 
Shetland form. 
It must be recognised that all such questions can only be authori- 
tatively solved by exploring also the allied species; only so can the 
amount of difference necessary to prove specific identity or otherwise 
be gauged, as, for instance, Hveres argiades and alcetas and Cupido 
minima have appendages that, at first glance, are absolutely identi- 
cal, but minute, constant differences can be detected that make them 
clearly three species. On the other hand, Plebiws egon has variations 
between individuals, even between the opposite clasps of one indi- 
vidual, that exceed in amount the difference that in the Everids just 
referred to distinguishes species. 
Mr. Pierce’s work will no doubt give an impulse to the study of the 
genitalia of the Lepidoptera, calculated as it is to give much assis- 
tance in their study. Though very complete, it nevertheless suggests 
various directions for further study; the marvellous structure of the 
“Vesica ” (Pierce), an investigation of the curiously aberrant forms 
in stlago and oxyacanthe, are only a little more obvious than many 
other points for investigation.—T. A. C. 
Critical Notes on the Classification of the Corduliine (Odonata). By 
J.G. Neepuam. Columbus, Ohio, December, 1908. ~(Annals 
of the Entom. Soc. of America, i. No. 4). 
WE have here a system of classification of the genera of the 
Corduliines of the world based on wing-venation. Two diagrams 
explain the terms employed. Students of the Odonata will find this 
short article of much interest, Mr. Needham having been so long 
at work on these insects.— W. J. L. 
