TO INDIAX CARCINOLOQT. 439 



European marine species Tahemon, while he places the freshwater forms in the genus 

 Bithynis, founded by Philippi in 1860. A reference to Fabricius's writings shows that 

 he, without naming any special type, described the freshwater forms first, and his name 

 Palcemon ought therefore to be taken for these ; this is tlie plan adopted by Dr. Ortmann, 

 who has recently prepared a useful and much needed revision of the genus. Ortmann 

 correctly limits the genus Bithynis to a single species, B. Gaudichaudii (Milne-Edw.), 

 from Chili and Peru, in which the hepatic spine is absent, and the chelipedes are 

 unequal and greatly enlarged. 



259. Leander longikostris (Say). 



Palcemon longirostris (Say), Milne-Edwards, Hist. Nat. Crust, t. ii. p. .'3'J-t (1837). 



Kurachi, four specimens {Brit. 3Ius.) ; Sunderbunds, four specimens ; Mergui, one 

 specimen {Bay) ; Gulf of Martaban, three specimens {Oates). 



The rostrum, which is upturned distally, exceeds the antennal scales by half or more 

 of its length; the basal crest ends opiwsite the articulation between the last two joints 

 of the antenuular peduncle. The hrst lower rostral tooth is placed under the most distal 

 tooth of the basal crest. The shortest of the three antennular tiagella exceeds the 

 antennal scales by more than half its length. On the carapace the antennal or upper 

 spine is minute, while the branchiostegal or lower one is well developed. The spine on 

 the outer margin of the antennal scale is placed at some distance from the apex, the 

 distance equalling nearly one tliird of the total length of the outer margin. 



The first pair of legs reach to or sliglitly exceed the antennal scales. The second legs 

 have tlie ischium and merus cylindrical and subequal, the carpus slightly shorter and 

 dorsally dilated ; the propodus is shorter than the carpus, and considerably swollen in 

 the adult of both sexes, with its outer surface suleate, and the sulcus bounded by two 

 ridges, an arrangement which is best seen on the distal two thirds of the hand, termi- 

 nating opposite the base of the mobile finger. The fingers are very long and slender, being 

 about half its length longer than the palm; they have sharp cutting-edges, but no teeth, 

 and are strongly curved at their apices. The remaining feet are slender and slightly 

 longer than the first pair. The last four abdominal segments are dorsally more or less 

 carinated. The telsou is dorsally smooth and rounded, with the very slender and acute 

 apex placed opposite the spine on the outer margin of the exopodite of the sixth pair of 

 abdominal appendages ; the two minute subterminal spinules are greatly exceeded in 

 length by the apex of the tclson. 



A female from the Sunderbunds is Ot mm. long from the orbit to the apex of the 

 telson, the rostrum 20 mm. long, the 'second leg 68 mm. long. 



The following are the rostral formulte in specimens from the diflFerent locjilities : — 



-^ , . 5 + 3 6 + 3 6 + 3 

 Kuvachi. jp, -^, -y-. 



6 + " • 5-1-2 



Sunderbimds. — Three specimens ^"5 one specimen -y-. 



Martaban. tt-, -tt— . 



Mcrgui. ^g— . 



62* 



