94 ANIMAL COLORATION. 



partly also from the contradictory results of experiments, are 

 so great that it does not appear to the present writer that we 

 are anywhere near a real understanding even of the problems 

 that have to be solved — let alone their solution. Dr. Seitz 

 has pointed out * that certain insects, for the most part pro- 

 tectively coloured, often select for their resting-places " quite 

 circumscribed situations on trees." Biston pilosarius, for 

 example, is constantly found, according to that writer, at a 

 height of I to 1 metre on tree trunks. The male of Hibernia 

 progemmaria sits for the most part at the foot of a tree, while 

 the female rests higher up — from 1^ to 2 metres. The same 

 regularity is observable among caterpillars : those of Saturnia 

 ■carpini frequent only the lowest boughs, while Staurojms fagi 

 selects the loftiest branches of oaks.t 



Since many birds habitually seek their prey upon different 

 parts of the tree,J and have, as has been pointed out already, 

 their likes and dislikes, we may often account for the preva- 

 lence of a well-disguised species not by the efficiency of its 

 disguise, but by its choice of a feeding-ground or a resting- 

 place. 



Protective Resemblance in an Annelid. 



In examining water from fresh-water pools and streams, it 

 is common +o meet with examples of a little worm belonging 

 to the Annelida Oligochmta, a group which also contains the 

 Earthworm. These worms, of which there are five species 

 known to occur in Great Britain, have received, on account of 



* Zool. Ja/iri., Abth. f. Syst, 1888, p. 63. 



t This fact may account for the rarity of the Lobster moth caterpillar 

 in England, I only saw, during five years' active collecting of Lepidoptera, 

 a single specimen of this larva. 



X Sitta searches for insects at the very foot of a tree, and in the herbage 

 round about. Dendrocopus investigates only the upper branches, etc., etc. 



