130 Proceedings of the Royal Society of Victoria. 



scattered setae, and also on the under margin of the second joint 

 there are about five very long straight setse pointing downwards 

 and forwards. 



As in the other allied forms mentioned they differ somewhat 

 from each other in the cutting edges, and other minor features. 



The left mandible (Fig. 4) has the cutting edge composed of 

 two rows of teeth, one on the inner side of the other ; they are 

 widely divided distally and united proximally. The outer one 

 consists of four sharp strong teeth, and the inner one of four 

 somewhat smaller teeth. Between these teeth and the base of 

 the molar tubercle the part is twisted somewhat, and on the inner 

 surface is a short outstanding process clothed with a double series 

 of 8-10 short spines. The surface of the molar tubercle is 

 slightly concave and square in outline, and the chitin is formed 

 into numerous small parallel ridges. 



The right mandible (Fig. 3) has the cutting edge consisting of 

 only one row of four strong sharp teeth ; on the inner surface, 

 between these and the base of the molar tubercle is a slightly 

 raised cushion, bearing three short, and one longer, stout 

 spinules, and near these is a bunch of five pectinated spines. The 

 right molar tubercle is somewhat longer than the left and the 

 surface somewhat smaller, but in other respects is similar. 



In use the cutting edge of the right mandible passes between 

 the double row of cutting teeth of the left mandible, and in so 

 doing incises the food, at the same time the molar tubercles meet 

 together to act as grinders. From the figures this is difiicult to 

 comprehend on account of the difiiculty of showing the twisted 

 distal half, the shading of which would obliterate the details of 

 structure. 



Lower Lip (Fig. 5). — The lower lip is similar to P. australis 

 consisting of two lobes, widely separate distally, but united proxi- 

 mally ; and the ends are rounded, and they and the inner margins 

 are densely fringed by inwardly pointing seta?, and the outer 

 margins fringed by much shorter seta?. 



First Al axilla. (Fig. 6). — The first maxilla agrees in outline 

 with P. australis and consists of two parts, of which the outer is 

 somewhat the longer and stouter ; they both curve slightly in- 

 wards ; the end of the outer lobe is truncate, and clothed with 

 eight or nine pointed spines which gradually become shorter from 



