16 Proceedings of the Royal Society of Victoria, 



size to one another, excepting the last two which are smaller, the 

 terminal one being the smallest. 



Seta? are scattered sparsely on the surface of the peduncle. A 

 row of seta? (1 auditory cilia) passes round the distal end of each 

 tiagellum joint. There are a few seta? on the tip of the terminal 

 joint. „ 



Second Antenna. — The pediuicle consists of five joints and is 

 about one fourth longer than the nagellum. The first joint is 

 much the shortest ; the second and third are equal in length and 

 short ; the fourth and fifth are longest and are equal in length. 

 The third joint is rounded on the ventro-internal aspect. A few 

 seta? are scattered spai'sely and irregularly over the segments of 

 the peduncle, with a row round the distal end of the fourth and 

 fifth. 



The flagelluin consists of 23-27 joints. Of these, the first is 

 much the longest, the next two or three are very slightly shorter 

 than the rest, which are sub-equal, and gradually become 

 narrower towards the distal end, where they increase in length. 

 There is an interrupted row of seta? around the distal end of 

 each joint. 



Upper Lip. — The upper lip is large and strong and is regularly 

 rounded at its distal end. It is divided into two portions. The 

 proximal has a median and two lateral elevations. The distal 

 part has a median depression and a raised rim. A strong trans- 

 verse ridge separates the distal from the proximal part. The 

 distal part is bent inwards to the mouth. There are a large 

 number of close-set seta? on the inner surface which slant towards 

 the median line. 



Mandible. — The mandible has the same general shape as in 

 P. anslralis, and the left one differs slightly from the right. 



The left mandible (Plate IV., Fig. 2) has a cutting edge formed 

 by two processes, both of which bear three strong, brown 

 teeth. Within these is a short process with a truncate end, the 

 somewhat circular margin of which is bordered by a row of 

 spiniform seta? about twenty in number. There are no seta? 

 between the base of this process and that of the molar tubercle, 

 such as occur in P. australis. The molar tubercle is columnar in 

 shape, with a squarely truncate end covered by a well-developed, 

 chitinous cap, which is slightly concave. The concavity is 



