Zoology.] 



NATURAL HISTORY OF VICTORIA. 



[ Insects. 



Pupa of female, twice the natural size, to show the temporarily long 

 sur-anal plate. The line below shows the natural size. 



M. M. Charpentier and Auclinet Serville long ago observed 

 that the larva? and pupa? of some species of Truxalis had a very 

 long, compressed, pointed sur-anal plate over the other abdominal 

 appendages, not present, or only of very reduced dimensions, in the 

 adult; the latter writer believing that this curious structural pecu- 

 liarity belonged only to the females, as it was wanting completely in 

 a male pupa in his possession. The same fact may be observed in 



the present in- 

 sect, in which 

 the upper abdo- 

 minal plate in 

 the adult female, 

 as figured in our 

 plate, scarcely 



exceeds the lateral plates in length ; but in the smaller individuals 

 in the pupa state, the same plate is as long and sharp-pointed as 

 the sub-anal plate of the males, equalling in length the 1\ last 

 joints of the abdomen (the 7th, 6th, and half of the 5th), as 

 represented in the above woodcut. What can be the significance 

 of this unusual change in relative size of this plate at different 

 stages of development, it is impossible at present to suggest. 



The terminal portion of the antenna?, equalling about 4 of the 

 preceding joints in length, has such obscure indications of joints 

 that the number is somewhat doubtful. 



Explanation of Figures. 



Plate 139. — Fig. 5, female, natural size. Fig 5a, side view of head and thorax, magnified 

 three diameters, showing structure of small mesothorax and large divided prothorax and 

 metathorax, with oblique sulci indicative of traces of undeveloped wings and elytra. Fig. 56, 

 under view of same, showing small spine on presternum and wide channelled sternum behind. 

 Fig. 5c, abdominal plates and appendages of same, magnified. Fig. 5<7, hind leg, magnified, 

 showing ridges, granules, and swollen tympanum near distal end. Figs. 5e and 5/, side and 

 inner views of middle tarsi of same, more highly magnified. Fig. 5g, side view of anterior leg, 

 similarly magnified. Fig. 6, male, natural size. Fig. 6a, sub-anal plate and abdominal ap- 

 pendages, magnified. 



Frederick McCoy. 



[ 154] 



