McLACHLAN'S CLASSIFICATION 19 



McLachlan classed the Leptocerida, Odonto- 



cerida, and Molannidce together in one family, 

 namely, the Leptocerida, and the Hydropsy- 

 chida, Polycentropida, Psychomyidce, and Philo- 

 potamidce in another family, with the general 

 name Hydropsychidce ; but he suggests that his 

 classification must not be considered final, and 

 that with greater knowledge of European and 

 extra-European forms, further subdivision of 

 families might become necessary. Continental 

 writers have adopted all his suggestions and 

 ideas to this effect. 



If the student is unable to decide from the 

 above general characters to which of the 

 families the insect under examination belongs, 

 he will derive assistance from the number and 

 position of the spurs of the legs, care being The spurs, 

 taken "to distinguish between the spurs, which 

 are usually long and transparent, 1 and the 

 spines, generally darker in colour, with which 

 species of certain genera are abundantly fur- 

 nished. Fig. 2 shows the position of the spurs 

 on the tibiae of Silo nigricornis. 



I have compiled a table based on these spurs, 

 and have found it of assistance in suggesting 

 the genera, to which reference may be made 

 when attempting to identify some unfamiliar 

 species. I give it on the next page. 



1 The spurs of a pair are not always equal in length, and 

 sometimes differ in form from each other. In some genera the 

 male has fewer spurs than the female, and a spur on one pair 

 of legs may be peculiar in form , as in the genera Colpotauliu$ 

 and Dipseudopsis, of which the former occurs in this country. 



