798 



STUDIES IN AUSTRALIAN NEUROPTERA, Vll., 



Viewed end on, it is more or less star shaped, being in the form 

 of a fairly regular polygon with concave sides. Typical doli- 

 chasters are shown in Text-fig. 7, a, b, and c. These structures 

 are very abundant all over the abdomen and thorax, excepting 

 upon the hard tergal plate of the pro thorax, on which only an 

 occasional one can be seen. 



The dolichaster is clearly a specialisation from a normal hollow 

 sensory hair or macrotrichion. This may be proved by a study 

 of the eighth and ninth segments of the larva. On the ninth 

 segment, the macrotrichia are of normal form. On the eighth, 



yv there are a few of normal form, 

 but most of them are slightly 

 "^ thickened and blunted at the tips, 

 and a few can be seen having the 

 projecting distal points or angles 

 of the true dolichaster-form. On 

 the seventh, the dolichaster-form 

 is fully established, but remains 

 very elongated, for the most part. 

 On the rest of the abdomen, all stages from a very narrow, 

 elongated dolichaster with only four or five rays, to a shorter 

 and stouter dolichaster with from seven to nine rays, can be 

 easily followed. 



Dolichasters vary from 40 to over 100/x in length, and from 

 about 20 to 30/x in extreme width distal ly. 



We may compare the dolichaster with the bulla, such as is 

 found in the larva of Micropteryx (Order Lepidoptera). In the 

 bulla, the macrotrichial chitin becomes very soft, and the internal 

 cavity is enlarged so that the hair expands into the form of a 

 soft, swollen bulb. Weak longitudinal supporting rays are, how- 

 ever, present, as may be seen by a careful examination of the 

 bulla under a high power. Moreover, when the bulla is viewed 

 end on, it, too, like the dolichaster, exhibits the star-shaped 



* Dolichaster.s from integument of larva of Ps. elegans (Gii^r. ), third 

 instar; ( x 330). a. Long, five-ra3'ecl form; h, four-rayed form; c, shorter, 

 seven-raj'ed form. Above h and c are shown four examples of micrasters, 

 also X 330. 



Text-fig. 7." 



