Mahicostracous Crustaceans from Malaysia. 255 



l>istr. 'I'ones Strait, Saiulwicli Islands, W. Australia, 

 Malay Arcliipelago. 



No. CCCLll. llah. Singapore. 



A young female. 



Dim. : Lcngtli S milliin., brcadtli l2'o. 



XI. Genus PoTAMON, Sav. 



14. Pvtumon {Perithtlphitsa) Butlikoferi^ de Man. 



Potamon (Pen'thelphusa) Biittikoferi, de Mau, Notes from the Leyden 

 Museum, vol. x.\i. pts. i.-iii. pp. 80-80, pi. vi. fi;,'. (1899). 



Dislr. Sintang. 



No. CCXCii. Bab. Mt. Matang, 3000 feet. 



A male. Dr. de Man describes the " iscliial line " on the 

 posterior maxillipedes as being parallel to the inner margin of 

 the i?;chial joint; in this example it is oblique, slanting away 

 from it from before backwards. 



Di7)i. : Greatest length 28'5 millira., greatest breadth 35, 



15. Potamon (^Perithelphusa) borneense, var. hilare^ dc Man. 



Potamon borneensis, var. hilaris, de Man, Notes Leyden Mu8. vol. xxi. 

 pts. i.-iii. p. 71, pi. v. fig. 4 (1899). 



Distr. Sintang. 



No. XCVIII. Ilab. Kuching : freshwater. 



A male. 



Dim.: Greatest length 18"5 millim., greatest breadth 23. 



16. Potamon (Parathelphusa) fridf-ntatum, 

 var. incertum, Lanchester. (PI. XII. Hg. 2.) 



Potamon {Parathelphusa) tridentatum, var. iiicertum, Lanchester, 

 P. Z. S. Lond. (1900). 



Jjit<tr. Singapore (Botan. Gardens). 



No.cxxxvi. Hob. Kuching: presumably freshwater, but 

 I have no note to that effect. 



A male, quite agreeing with the forms I have already 

 described from Singapore ; though in this specimen the 

 lobulation of the extraorbital tooth is even more striking, 

 giving it all the appearance of having four antero-lateral teeth, 

 such that the second is truncated, while the rest are sharp. 



J>wi. : Lengtli (including rostrum) 30-5 millim., breadth 

 bi'twren l;i<t teeth .'^7".'). 



