INFLUENCE OF LIGHT ON COLOUR. 95 



of these Beetles, belonging to the typical genus, is drawn on 

 Plate IV. Fig. 7, and is shown as crawling on the top of one of 

 the mushrooms. Its name is Choleva angustata. 



The genus, of which there are seventeen British species, is 

 known by its narrow body, its long and slender legs and 

 antennffi, the very obtuse hinder angles of the thorax, and the 

 oval and striated elytra. The insect is represented of its natural 

 size, which seldom varies much from one-sixth of an inch in 

 length. The head is black and shining, the thorax is pitchy- 

 black, becoming greyish at the margins and posterior angles. 

 The elytra are rather variable in colour, black being the lead- 

 ing hue, but taking shades of red or grey according to the 

 individual. The apex is round and short, and each elytron is 

 marked with seven faint atrioe. The legs are pale reddish- 

 yellow. The body is covered with a very fine and very short 

 yellowish down. 



It is not uncommon to take a specimen that is pale rusty- 

 red or yellow, the reason for this paler hue being that the 

 Beetle has only recently emerged from the pupal state, or that 

 the atmosphere has not exercised its full influence upon it. 

 When it has been exposed for a few days to the air and light, 

 the reddish-yellow will change to the dark-red or grey-black 

 which is the usual colour of the Beetle. 



Next comes the family of the Scydmcenidce, of which we 

 shall take one example, namely, Scydmcenus [Eumicrus] 

 tarsafus, which is shown on Woodcut X. Fig. 2. These insects 

 are all very minute, the present species, though only the twelfth 

 of an inch in length, being the largest of the family. They 

 are all covered with down, are without wings, and have the 

 elytra coming completely to the end of the abdomen. The facets 

 of the eyes are very boldly marked, and the peculiar form of the 

 antennae, which are terminated with three very large joints, 

 each increasing in size, may be seen by reference to the same 

 illustration, Fig. a. The maxillary palpi are very conspi- 

 cuous. 



The head and thorax of this species are black, and the elytra 

 are very deep chestnut. Like the rest of its kin, it is to be 

 found in hotbeds, leaf-heaps, cucumber frames, and similar 

 localities. The name Scydmcenus is Greek, and yignifies ' sullen 



