DUTCH BORNEO-EXPEDITION. 103 



and the distance between the external orbital angles or 

 that between the epibranchial teeth. The extraorbital tooth 

 is comparatively larger. In the female the distance be- 

 tween the external orbital angle and the tip of the epi- 

 branchial tooth measures just one eighth part of that 

 between the external orbital angles ; in the male from 

 Mount Damoes, however, one sixth, but perhaps may this 

 difference be attributed to the different size of these spe- 

 cimens. In the female the free border of the front mea- 

 sures exactly one third the length of the carapace, just 

 as in the type-specimens of Pot, sinuatifrons ; in the male 

 from Mount Damoes it is, however, considerably 

 broader and such a specimen was described by Miers 

 (1. c). The front, the frontal margin, the orbits and their 

 margins fully resemble, however, those of the female ; the free 

 border of the front (Plate 6, Fig. 10^^ and Plate 9, Fig. 10*) 

 presents three very shallow bays, the middle of which is 

 not deeper than the lateral. 



The postfrontal ridge is a little less salient, but for the 

 rest agrees with that of the female. The grooves between 

 the gastric region and the epibranchial are not so deep. 

 The median process of the posterior border of the epi- 

 stome has a different form in the male and in the female 

 (Fig. iOf and Fig. 10^), but this is also the case in the two 

 specimens of Pot. sinuatifrons, in the larger one it is 

 triangular about as in the female from the Upper Sibau, 

 but in the smaller specimen its form agrees very well with 

 that observed in the male from Mount Damoes. This dif- 

 ference therefore cannot be a sexual one. The posterior 

 margin of the epistome is transverse in Pot. sinuatifrons, 

 but both in the male and in the female o? Pot. consobrinum 

 it runs on each side slightly backwards. 



The lower surface of the carapace and the outer foot- 

 jaws fully agree in both individuals. 



The abdomen (Fig. 10») resembles that of Pot. sinuati- 

 frons. The terminal segment is a little shorter than its 

 base is broad, the lateral margins are slightly convex, the tip 



Notes from the Leyclen Museum, Vol. XXI. 



