20 Mr. Rennie on the Cleanliness of Animals. 



conjecture what had made it take a fancy to so singular a 

 helmet ; but I soon perceived that it was in fact making prey 

 of the poor snail having, for that purpose, thrust its narrow 

 extensile head half to the bottom of the shell, which it did not 

 quit till it had devoured the inhabitant. 



It was thus proved to me that it was not a vegetable feeder, 

 but carnivorous ; and I subsequently found, upon trial, that 

 it would touch no animal except snails. Its head, from being 

 extensile, is well adapted for pursuing its prey to the inmost 

 recesses of their shells ; and its mandibles, which are curved in 

 form of a pair of calliper compasses, appear, as in the in- 

 stance of the grub of the ant-lion (Myrmeleon formicarius}, 

 to be employed rather for sucking than for eating, though I 

 was unsuccessful in satisfactorily ascertaining this point. 



Head of the glow-worm grub, a, the head ; b, the neck ; c, the antennae ; d, the jaws. 



It is more to the present subject to mention, that the grub 

 cannot well devour one of its victims without being soiled with 

 slime ; and accordingly, after every repast, I observed that it 

 went carefully over its head, neck, and sides, with its cleaning 

 instrument, to free them from slime. 



Though not directly connected with my immediate subject, 

 it maybe interesting to many 'readers to mention that the above 

 grub, as well as those observed by Baron de Geer, distinctly 

 proved the fallacy of the common doctrine respecting the light 

 of the glow-worm, which goes to maintain that it is a lamp, lit 

 up by the female, to direct the darkling flight of the male. 

 ' Ce sont,' exclaims Dumeril, ' les flambeaux de 1'amour des 

 phares des telegraphes nocturnes qui brillent et signalent au 

 loin le besoin de la reproduction dans le silence et Tobscurite 

 des nuits *.' Mr. Leonard Knapp, refining upon this notion, 

 conjectures that the peculiar conformation of the head of the 



* bictionnaire des Sciences Naturelles, xxv. 216. 



