THE BIONOMICS OF AUSTKALIAX TABAXIDAE. 47 



For about three days following their emergence the young larvae do not feed, but 

 remain on the surface him. After this period, however, they commence to attack 

 each other, even in the presence of an abundant supply of small shells and other 

 animal life introduced upon aquatic plants. 



When twelve to fourteen days old the majority of the larvae measured from 



6 mm. to 7 mm. in length, by 0-7 mm. to 0-85 mm. in width ; the groups of hairs on 

 the syphon tube increased to four or live, and Graber's organ contained either two or 

 three pairs of bodies, each pair diminishing in size from the anterior end. A few of 

 the larvae had developed very slowly during these twelve days and now measured 

 only 4-5 mm. in length. In two larvae (7 mm. and 8-5 mm. in length respectively) 

 a second pair of mandibles could be distinguished in the anterior third of the first 

 segment, and faint traces of the dark bands characteristic of older larvae of this 

 species could be detected near the junction of the segments and near the anal 

 protuberance. The second ecdysis apparently takes place when the larva is between 



7 mm. and 9 mm. in length. Unfortunately the number of larvae in this batch 

 became so reduced, largely owing to cannibal practices, that specimens could not be 

 secured as frequently as desired to determine this point, but a " wild " larva captured 

 on 2nd March appeared to represent an early stage of the third instar and to connect 

 the last-described individuals with older ancl more advanced ones of the same batch. 

 This larva measured 9 mm. in length by 1 -5 mm. at the widest part ; the junctions 

 of the segments were banded and blotched with dark brown, and the dorsal tubercles 

 and the pseudopods bore short bristle-like hairs, as in older larvae. 



On 2nd March, or when 49 days old, two larvae of the original batch measured 

 15 mm. and 16 mm. in length respectively. WTiether the subsequent changes in the 

 larvae follow ecdyses, or whether they are developed gradually during the third instar, 

 has not yet been satisfactorily determined. On 16th April, or when 94 daj-s old' 

 two other larvae of this batch were destroyed by their fellows. The former now 

 measured 21 • 5 and 24 mm. long by 3 and 4 mm. wide respectively. The brown bands 

 and blotches are now very distinct and of the same pattern as in adult larvae ; the 

 striae are well marked on all segments, but are absent on the brown areas ; the man- 

 dibles are black ; the bunches of stout curved spines above the insertion of the antennae 

 are pale ferruginous, very prominent, and overhang what appear to be moderately 

 large facetted eyes situated behind them ; in the smaller of the two larvae there are 

 five pair of bodies in Graber's organ, in the larger six pairs ; the stigmal plate is now 

 visible at the apex of the syphon tube. About the anterior third of the first segment 

 (prothoracic) there are several long branched hairs, on other segments they are simple 

 or absent ; the pseudopods are prominent ; there are no hairs on the anterior margin 

 of the thoracic segments, these being confined to the dorsal ridges and pseudopods 

 of the abdominal segments, where they are inconspicuous. The dark bands and 

 blotches are formed entirely of very short and dense pile, as in the younger larvae ; 

 the pseudopods were very prominent in the larger of the two larvae. 



On the same date (16th April) the contents of the breeding-tray were collected, 

 with the object of separating the remaining larvae of T. aprepes and several larvae 

 of T. nigritarsis which had been placed in the tray recently. The former now 

 numbered only five, two of which measured about 28 mm. long and three about 

 33 mm. long. One of the latter was retained for examination and is described below, the 

 others were put separately into five-inch flower-pots half full of moist, clean granite 

 sand, upon which lily leaves and shells were placed every three or four days. The 

 larva referred to above was 94 days old at the time of its death, and measured 33 mm. 

 in length and 5 mm. in width. In size and coloration, as well as in external form, it so 

 closely resembles the mature larva which has undergone a long resting period that a 

 description of it will suffice for both. There are six prominent pseudopods to each 

 segment from the fourth to the tenth inclusive, arranged on the anterior margin, three 

 on each side of the median line ; each pseudopod is armed with a number of short 

 bristle-like hairs ; on the dorsal surface of the same segments there are two transverse 



