Descriptions of some Australian Pliyllopoda. 9 



terminal part clothed on the lower face with numerous small 

 olfactory papillæ and terminating in 2 small bristles. 



Of antennæ I have failed to detect even the slightest 

 rudiment. 



The oi^al parts (see fig. 2) are crowded together on a com- 

 paratively restricted area just behind the frontal duplicature. 

 They consist of a well-developed anterior lip, a pair of strong 

 mandibles, a posterior lip, and 2 pairs of maxillæ Of these 

 parts, the anterior lip and the mandibles are very easy to 

 examine, whereas the succeeding parts cannot be fully examined 

 without a most careful dissection, and would also seem to 

 have been misinterpreted by most authors, both in the genus 

 Aptis and Lepidurus. 



The anterior lip, or labrum (see fig. 2), forms a rather 

 large, oval quadrangular flap, convex below, and issuing from 

 the somewhat inflected middle part of the frontal duplicatiu-e, 

 to which it is movably articulated. It covers below the 

 masticatory parts of the mandibles, and terminates with a 

 somewhat trilobate and finely ciliated edge. 



The mandibles (see figs. 2 & 4) are very strong, and, like 

 the labrum, easily observable in the ventral aspect of the 

 animal, as 2 transverse, rounded prominences extending on 

 each side of the labrum. Their body (see fig. 4) is navicular 

 in form, exhibiting a roomy cavity filled up by the strong 

 adductor muscle, and terminates distally in an obtuse point, 

 by which it is movably articulated to the mandibular segment. 

 The masticatory part is somewhat expanded, and exhibits a 

 rather broad cutting edge divided into about 8 strong, bifurcate 

 teeth of a dark corneous hue. Of a palp, no trace is to be 

 found in the adult animal. 



The posterior lip (fig. 5), occurring close behind the 

 masticatory parts of the mandibles, is rather small and of a 

 somewhat membranous consistency, being composed of 2 sym- 

 metrical halves connected in the middle by a thin membrane. 



