THE HIDDEN TYPE OF WING-GROWTH 119 



with strong, sharp teeth adapted for seizing prey, maxillae 

 in which all the typical parts can be distinguished, and a labium 

 with mentum, palps and ligula. The long, well-formed 

 thoracic legs have each a definite foot-segment, marked off 

 from the shin and carrying two claws. As this larva lives 

 submerged, it needs special organs for breathing, and these are 

 found in seven pairs of elongate jointed appendages attached 

 on either side of the body at the front edge of the first seven 

 abdominal segments ; each of these slender gill-limbs is 

 traversed by an air-tube which gives off fine branches, 

 and two such tubes run side by side into the long, hollow 

 tail-process, attached to the ninth abdominal segment, which 

 also has, apparently, a similar respiratory function. 



Among other families of this order, such as the " ant-lions," 

 lacewings, and their allies, a modification of larval type is 

 found associated with a small number of moults and a habit 

 of feeding by suction, so that the body increases markedly in 

 size during each prolonged stage of the life-history. As an 

 example of this group, an Australian species of Psychopsis, 

 whose transformation has recently 1 been described in detail, 

 may be taken. The newly-hatched larva (Fig 68 a) has a 

 broad, flattened, quadrate head which bears seven-segmented 

 feelers and long, slender, acute mandibles and maxillae ; the 

 body with pale relatively feeble cuticle is no broader than the 

 head and only about thrice as long, tapering to the tail-end. 

 The legs are elongate, each with a single foot-segment that bears 

 two short, pointed claws and a long sucker process. The jaws 

 of this larva are most remarkable, the maxilla (Fig. 68 mx), 

 with very small cardo and stipes and no palp, has a long, sharp, 

 curved blade of nearly the same shape as the grooved mandible 

 (Fig 68 mn) beneath which it rests so as to enclose a channel ; 

 through this juices from the insects captured and impaled are 

 sucked into the stomach. The larvae of this group discharge 

 no excrement, and as the first stage in Psychopsis lasts for 

 eight months and the little creature feeds greedily except during 

 its winter rest, its body swells to more than twice its original 

 length and breadth, so that the head appears relatively small 

 and the legs short as (Fig. 68 b) the first moult becomes due. 



1 R. J. Tillyard : " The Life-history of Psychopsis elegans ". Proc. 

 Linn. Soc. N.S. Wales, Vol. XLIIL, pt. iv. 1918. 



