1901.] CEUSTACEAN FBOM THE SOUDAjST. 99 



The carapace is somewhat less enlarged and, according to A. Milne- 

 Edwards, " aplatie transversalement " (in the specimen that lies 

 before me the upper surface of the carapace is broken !). The 

 postfrontal crest shows different characters. When the cai'apace 

 is looked at from above, the whole upper margin of the orbits, 

 the whole extraorbital tooth, and also that between the latter and 

 the small epibranchial tooth remain visible. The postfrontal 

 crest is somewhat obliquely bent backwards a little beyond the 

 outer angle of the orbits, and unites with the antero -lateral margin, 

 which shows here a very small, granuliform, epibranchial tooth. 

 The extraorbital tooth is larger, slightly concave, obtuse, directed 

 forward, and its outer margin is slightly convex and makes a 

 right angle with the upper margin of the orbits. The distance 

 between the outer angle of the orbits and the epibranchial tooth is 

 proportionately longer than in Potamon Jloweri, namely almost as 

 long as the orbits are broad ; the tooth between the outer angle 

 of the orbits and the epibi-anchial tooth is much longer and has a 

 different shape. This tooth is longer, but lower, less salient than 

 the extraorbital tooth, its outer margin is slightly arcuate and its 

 very short anterior margin measures only one third the length of 

 the outer margin. The granulations of the antero-lateral margin 

 are smaller and less prominent than in the new species from the 

 Soudan. The lower margin of the orbits runs almost transversely 

 in P. Jloweri, but somewhat obliquely upwards in P. auhryi. 

 The sternum of the male is not thickened along the insertion of 

 the chelipedes. The abdomen of the male has a different form. 

 The terminal segment measures only two-thirds of the penulti- 

 mate, and its length measures two-thirds of the width of its 

 posterior margin. The penultimate segment is, in the speci- 

 men of Pot. auhryi lying before me, 9 mm. long, the anterior 

 margin measures 9| mm., the posterior 12 mm., namely the 

 straight line that unites its lateral angles, the margins being con- 

 cave : the penultimate segment is as long as its anterior margin 

 is broad. 



The tubercles with v\'hich the margins of the meri of the cheli- 

 pedes are furnished are, in P. auhryi, smaller, less prominent, 

 and the tubercle on the under surface of these joints near the 

 carpal articulation appears as a rounded granule, scarcely larger 

 than those that surround it. The lingers are somewhat shorter 

 in proportion to the length of the palm, and the dactylus is not 

 granulate on its upper margin. The meropodites of the ambu- 

 latory leg-S are a little more enlarged, those of the fifth pair are 

 20 mm. long and 7| mm. broad; the dactylopodites finally present 

 one spinule more on their posterior margin. 



Potamon {Potamonautes) pelii Herklots, from the Gold Coast, is 

 also a different species. A young male, type, from the Leydeu 

 Museum, is lying before me. The carapace is much less enlarged; 

 the postfrontal crest runs otherwise, as each half does not extend 

 from the mesogastric suture, transversely outward, but somewhat 

 obliquely backward ; the postfrontal ridge, as in P. auhryi, unites 



