on the Genus Myllasna. 35 



structural differences are absolutely necessary to separate the 

 species ; a slight variation in size, although useful as an auxiliary, 

 cannot l)y itself be considered sufficient. I must however arid 

 that I have not seen any authentic type of M. vi'mima, though 

 many British specimens agree entirely with Dr. Kraatz's 

 descriptions. In Mr. TNLison's collection tliere is a specimen of 

 3L. intermedia, which differs from the normal type of that 

 species in characters precisely similar to those on -which 

 Dr. Kraatz separates M. minium from M. infuscata. 



All, except one, of the British species of Mylhcna, are very 

 similar in their habits of life ; they may be found in damp moss, 

 or at the roots of herbage growing on the margins of either 

 pools or running water. The only exception to this rule, as far 

 as I know, exists in M. elongata ; the habits of that species 

 resemble those of the Bledii and Heteroceri, with whom I have 

 generally found it associated ; like them, it conceals itself in 

 mud, especially that of a cla}'ey nature, at the margin of stagnant 

 water, and may be obtained in the same way, by pressing lightly 

 the mud with your foot ; it Avill then immediately emerge from 

 its hiding place, and running with extreme velocity for a short 

 distance, will eventually open its wings and fly awaj^. 



The dimensions of the variotis species of this genus, as given 

 by Dr. Kraatz and other authors, can only be used comi)aratively, 

 having generally been taken from dried specimens more or less 

 contracted, they can in no case be regarded as representing the 

 the true length of the insect. In the following descriptions the 

 measurements have been made from specimens restored to their 

 life ft)rm, and therefore very mtich exceed the length given in 

 previo.us descriptions. 



NotAvithstanding their similarity of colour, there is not much 

 difficulty in distinguishing the various species of Mylhvna, if due 

 attention is paid to the comparative developement of the parts of 

 the body, especially of the thorax and elytra. It is chielly 

 among the smaller species that confusion exists; but even when 

 the abdomen is so much contracted that its trtie shape becomes 

 lost, they may still be distinguished by a careful comparison of 

 the antenna?, thorax, and elyli-a. For this purpose the following 

 characters of the four smaller species will be fotmd very useftil. 



c 2 



