The Scottish Naturalist. 65 



OUTLINE DESCRIPTIONS OP BRITISH COLEOPTERA. 



(Continued from p. 17.) 

 By Rev. T. BLACKBURN, B.A. 



[As it is possible that some readers of the " Scottish 

 Naturalist" who would like to make use of the "tables" 

 in the " Outline descriptions of British Beetles," may not be 

 sufficiently familiar with the dichotomous system, it may be of 

 advantage to describe the process that should be gone through 

 in order to arrive at the name of a species. For this purpose 

 we will take an example, and suppose that a collector is endea- 

 vouring to identify by the descriptions — say a specimen of 

 Cychrus rostratus. He will act as follows : — 



1st. He will turn to the " Table of Groups" (p. 13), in order to 

 discover to which main division of the Coleoptera his specimen 

 belongs. In this table, under the figure 1 (on the left hand 

 side of the page), beetles are divided into two classes ; one con- 

 taining species whose elytra reach considerably beyond the 

 insertion of the 3rd (or hind) legs ; the other, species in which 

 the elytra are much shortened. Finding his specimen to belong 

 to the first of these classes, he will be referred (by the figure 2 

 on the right hand side of the page) to the place where there is 

 a separation into classes of the species whose elytra reach con- 

 siderably beyond the insertion of the 3rd legs. (This will be 

 where the figure 2 occurs on the left hand side of the page). 

 There they are split into the following divisions, viz. — (a) those, 

 none of which have the antennae clubbed, which are not aquatic, 

 and which have tarsi easily seen to consist of five joints ; (p) 

 those having the antennae not clubbed, not being aquatic, and 

 having tarsi easily seen to consist of four joints ; (<;) aquatic 

 species ; (d) a residuum not possessing all the characters of any 

 one of the other divisions under the figure 2. By comparison of 

 the specimen under enquiry with the characters of these several 

 groups, it is seen to belong to the first of them, against which, 

 on the right hand side of the page, is set the figure 3. Turning 

 to the line where the figure 3 occurs, on the left of the page, it 

 will be seen that the species attributed to that number are 

 divided into two groups — one having the anterior tibiae simple, 

 the other having them either notched on the inner side or with 

 a spine at the apex. As the specimen will be found to have a 



