572 PROF. W. J. DAKIN ON 



from Natal, so that South Africa has also a representative of the 

 genus. It is surprising to find that, on the whole, there are only 

 slight differences between the Australian species and P. varians 

 from Europe or the species known from the American continent. 



Habitat in West Australia. — Specimens of P. australis were 

 first met with at Northam, a small town inland on the plateau, 

 about 70 miles from the coast and at an elevation of roughly 

 500 feet. They were captured in the River Avon, where it breaks 

 up into small channels below the weir. The water is of course 

 quite fresh. The largest specimens obtained have been caught 

 at the above place, and the animal is quite plentiful at all seasons 

 of the year. Large-sized specimens have also been captured in 

 Gin Gin Brook, about 50 miles north of Perth and at an elevation 

 of roughly 300 feet. Mr. W. B. Alexander, M.A., of the West 

 Australian museum, has placed in my hands collections captured 

 in Bibra Lake and the Serpentine River. The lake is a small 

 expanse of water only a foot or so deep, if that in the dry season, 

 and is situated on the coastal plain not so very far from the sea. 

 The habitat of these lake specimens is very different from that of 

 the Northam examples, and there is a characteristic difference 

 in the size of the individuals, those from the Northam River 

 being the larger. The average length of the individuals caught 

 at Northam is 32 mm., against 20 mm. for the Bibra Lake type. 



The Serpentine River is about 34 miles south of Perth, and 

 the specimens were caught where the river leaves the hills and 

 enters the coastal plain. The specimens from Northam are 

 described and figured as the type specimens of Pakemooietes 

 australis. 



Description". 



Body stout. Le]igth of largest specimens 39 mm, from end of 

 telson to tip of rostrum, and 72 mm. to tip of outstretched antennae. 

 The living animals are transparent, with a preA'ailing amber-green 

 tint. Brown pigment flecks occur laterally on the posterior 

 margins of the abdominal terga, and there are sometimes two 

 delicate longitudinal lines on the carapace somewhat laterally 

 situated. The carapace is not quite so long as the last three 

 abdominal segments. The sixth abdominal segment is almost 

 twice the length of the fifth. 



Rostrum. — The rostrum is long and about equal in length to the 

 carapace, biit may be very slightly longer or shorter. The tip of 

 the rostrum exceeds the distal margin of the antennal scales. 

 The rostrum is laterally compressed and has a pronoimced 

 curvature trending upwards towards the apex, A few small 

 chromatophores are present. The dorsal armament consists of 

 usually five or six teeth which are almost equally spaced along 

 the entire length of the rostrum. This is without counting a 

 distal tooth which forms the upper poi'tion of the bifid apex. 

 The most posterior dorsal tooth is well behind the orbital notch, 

 and the next one is immediately over it. There are three or four 



