44 NATURAL HISTORY OF AQUATIC INSECTS CH. 



solid parts, which assuredly could not pass through 

 the fine openings of the mandibles." l 



Other examples of perforated mandibles were also 

 described. Reaumur, 2 in his account of the Ant-lion 

 (Myrmeleon), affirmed that this predatory larva had 

 no true mouth, and that the juices of its victims 

 could be absorbed only through the hollow mandibles. 

 When he comes to the lace-winged flies (Hemerobidae) 3 

 he says of them that they have mandibles like those 

 of the Ant-lion. This statement has been confirmed 

 by Ratzeburg, who compares the mandible of the 

 Hemerobius-larva to the poison-fang of a serpent, 

 and says that he saw fluids pass along the internal 

 cavity. 4 The larva of Gyrinus furnishes us with 

 another instance. 



Siebold 5 at length combined these statements in 

 the following sentence : " The mouth of the larvae 

 of Myrmeleontidae, Hemerobidae, and Dytiscidse is of 

 very singular construction. There is no oral opening, 

 and the mandibles and maxillae are altogether unfit 

 for mastication, the mandibles being converted into 

 two curved hooks, which are hollow and provided 

 with a narrow fissure at their tips. The larvae bury 

 these hooks in the Insects which they seize, and 

 through the cavities of the organs, which communicate 

 at the base with the oesophagus, suck the blood." 

 Siebold's authority gave fresh currency to this state- 



1 Me moires, Tom. IV. p. 386. 



2 Tom. VI. p. 340 (1742). 3 Tom. VI. p. 382 (1742). 



4 Ratzeburg, Forstinsekten., Bd. Ill, p. 243 (1844). He does 

 not say that in this larva the mouth is closed. 



5 Lehrb. d. vergl. Anat. 



