6 THE NORTHERN MICROSCOPIST. 

like Ephemera and Ceznis. It may swim actively like Cloéon and 
Baetis ; or creep, like Leptophlebia and Ephemerella. ‘The form 
and position of the gills must be noted ; and also the mouth, with 
the number of joints on the palpi, and the form of the legs, 
antenne, and tails. 
The species are determined by slight modifications of structure, 
combined with variations in colour and markings. The three 
species of Ephemera, viz: 2. danica, vulgata, and /ineata, may be 
readily recognised by the difference in the marks on the abdomen. 
Most authors on Entomology have described a few species of 
the Ephémeride, and have mixed up their names in almost hope- 
less confusion. The best works for the student are F. J. Pictet’s 
“Histoire Naturelle des Insectes Néuroptéres: famille des Eph- 
émérines,” which has not been translated into English; and the 
Rev. A. E. Eaton’s “ Monograph on the Ephemeridze,” published 
by the Entomological Society, in which the descriptions of the 
genera and species are in Latin. The latter is the best work for 
classification, the principles and nomenclature of which I have 
adopted in this paper. 
Specimens of the Ephemeridz found in museums are often 
dried up beyond recognition, their soft bodies becoming changed 
in form as well as colour. In the British Museum they are kept 
in a cabinet, which contains about two hundred specimens, British 
and foreign ; they have been arranged by Mr. Eaton. To preserve 
the imago, he recommends it to be dipped in dilute spirits, and 
then transferred to a tube partly filled with water, to which a drop 
or two of glycerine should be added each day until the tube be 
full. A drop of acetic acid will prevent fungoid growth. A few 
of the specimens in the national collection, contributed by Mr. 
Eaton, are preserved in this way. 
The microscopist will find this family of insects one of absorbing 
interest, many of them being of exquisite beauty. 
W. BLACKBURN. 


