INVERTEBRATE ANIMALS. 89 



^ig^keitt^ ^nhh Case. 



The Mark ^ indicates specimens or other illustrations exhibited in the Cases. 



Group 205.— GEOMETRINA. yn, the earth; fj^kpov, a 

 measure. The name alludes to the mode of progression 

 adopted by the larvae, which are called loopers because 

 in moving they- alternately take the form of the Greek 

 letter H and extend themselves at full length. 



The females of certain species are without wings. 

 GeometrcB, of which about 270 kinds inhabit Britain, 

 are sometimes seen in the cold grey light of a winter 

 evening, but more characteristically they are the butter- 

 flies of the summer twilight. Whilst the Noctuce and 

 other more robust moths, passing swiftly by, seem 

 always in haste, these slender and delicately coloured 

 insects flutter leisurely along the hedge-side in the 

 gloaming, apparently in a condition of perfect enjoy- 

 ment. 



Upper Compartment. 



Specimens of preserved larvae, showing protective 

 mimicry. 



Section BOMBYCINA. /3o>/3y^, the silk-worm. 

 Group 206.— Genus SATURNIA, and allies. This group 

 includes amongst its constituents upwards of 40 silk- 

 producing moths, the larvae of which secrete the silk in 

 two large intestine-like vessels which unite at the mouth 

 in a common tube called the spinneret; through this 

 tube is ejected the secretion which, as soon as it comes 

 in contact with the air, hardens into a shining fibre 

 known as silk. 



Observe the configuration of the shaded pattern in 

 Brahmcea and the talc-like spot in Attacus Atlas. 



H 



