88 CRUSTACEANS OF IHE 



concave, the free border being not curved upwai'd ; the 

 surface is somewhat granular. 



The upper margin of the orbits has the same form and 

 direction as in Pot. borneense var. hilaris and is not si- 

 nuous, as is the case with Pot. Büttikoferi; it forms a 

 right or somewhat obtuse angle with the outer margin of 

 the extraorbital tooth. The orbits and the eye-peduncles 

 resemble those of the variety hilaris, the lower margin 

 shows no notch near the outer angle, the inner angle is 

 obtuse and little prominent. The external angles are ob- 

 tuse and reach almost as far forward as the frontal margin ; 

 they are comparatively a little less distant 

 I'rom the epibranchial teeth than in Pot. borneense 

 and its variety hilaris, so that the extraorbital 

 tooth appears shorter. In the species described by 

 von Martens the outer margin of the extraorbital tooth, 

 from the outer angle of the orbits till the base of the 

 epibranchial tooth, appears distinctly longer than 

 the orbits are broad, but in Pot. silvicola just 

 as long. The outer margin of the extraorbital tooth 

 appears in most specimens slightly convex, but in others 

 it has the same form as in Pot. borneense var. hilaris and 

 the notch that separates it from the epibranchial tooth 

 is just as deep. The epibranchial teeth are acute and 

 salient, the lateral margin curves slightly outwards, so that 

 it appears a little more convex than is usually the case 

 in Pot. borneense and its variety. The oblique wrinkles 

 are in both species numerous and moderately salient. The 

 front-orbital and the lateral margins of the carapace are 

 smooth, entire. 



As regards the nasal plate, the epistome, the outer 

 maxillipedes and the pterygostomiau regions, there is no 

 difference between both species. As in Pot. borneense var. 

 hilaris, the median tooth of the epistome is triangular, 

 acute, there is also a granular line dividing the subhepa- 

 tic from the subbranchial region and these regions as also 

 the branchiostegite carry the same rugosities. The ischial 



Notes from the Leyden Museum, Vol. XX.I. 



