126 CRUSTACEANS OF THE 



is lying before me , is a different species. In this form, 

 indeed, there is an epibranchial tooth ; the front is much 

 broader than the orbits and appears more enlarged, with 

 the lateral margins more oblique. The postorbital groove 

 is much deeper and the cephalothorax is much narrower 

 posteriorly than anteriorly, that is not the case in Potainon 

 Burgert. The dactylopodites of the ambulatory legs have 

 about the same form in both species, but they are longi- 

 tudinally ridged above in the Australian species, smooth in 

 Pot. Bilrgeri and the propodites of these legs are some- 

 what more slender in the latter. 



The Borneo-collection contains also a female without 

 eggs, unfortunately the locality has not been indicated. 

 This specimen very probably belongs to the same species 

 though it shows a few slight differences (Plate 12, Fig. 

 \^g). In the male, described above, the upper orbital 

 margin runs very slightly backwards, in the female 

 however slightly forwards. The epigastric lobes are ill- 

 defined. The ambulatory legs are a little more slender, as will 

 be seen by comparing the measurements. The chelipedes 

 seem to present only the usual sexual differences. The 

 right chela is somewhat larger than the left; it is less 

 high than that of the male, the granulation extends almost 

 over the whole surface of the palm and the index is very 

 slightly grooved. The smaller chela agrees with that of 

 the male, but the granulation is more distinct. The female 

 has a somewhat larger size than the male. 



Measurements of both specimens : 



Length of the cephalothorax 10', 111 



Distance hetween the external orbital angles 9;| 10 { 



Greatest width of the cephalothorax anteriorly 13', 15[ 



, ,/ // ,. ,/ posteriorly . 13 V 15^ 



Breadth of the posterior margin of the cephalothorax .... 7 ,' 9 



Breadth of the free border of the front. ...'.... 3 [ 3 



Height of the front i. e. the distance, in the median line, between 



the epigastric lobes and the frontal margin 1] 2 



Thickness of the cephalothorax 71- 81 



Breadth of the orbits 31 3', 



Height . » ,/ ... 2 2 



JS^otes from the Leyden JMuseum, Vol. XX.I. 



I 



