224 J. G. DE Man : The Fauna of Brackish Ponds. [Voi,. Il^ 



specimens with one apical tooth are as numerous as those the ros- 

 trum of which carries two apical teeth, and that the lower margin 

 usually is armed with 7 or 8, rarely with 6 or 9 teeth. According 

 to Milne Edwards the rostrum should carry 6 or 7 upper teeth 

 proximally and as many on the lower margin, but it is remarkable 

 that he makes no mention at all of the apical tooth or teeth. Gene- 

 rally the two first teeth are placed on the carapace, only in two 

 specimens from Calcutta one tooth is placed on the carapace, and 

 in a single specimen from the same locality the three first teeth 

 are placed upon it. The apical tooth or teeth, which are much smaller 

 than those on the proximal part of the upper margin, are usually 

 separated from the latter hy a lojtg smooth interspace, which is as 

 long as the distance between the foremost proximal tooth and the 

 anterior margin of the carapace, rarely somewhat shorter than 

 that distance ; rarely, i.e., in 11 out of 56 specimens, the foremost 

 proximal tooth is placed on the smooth interspace, about midway 

 between the preceding and the apical teeth. In the largest specimen 

 from Port Canning (fig. 4), the rostrum of which presents the 



toothing formula "- , the foremost proximal tooth of the 



upper margin is placed just above the first of the lower, immediately 

 infrontof the distal end of the first joint of the antennular peduncle; 

 in other individuals the foremost proximal tooth is situated more 

 or less in front of the first tooth of the lower margin ; the proximal 

 teeth of the upper as well as those of the lower margin are equi- 

 distant, and the former are larger than the latter. The rostrum, 

 is moderately broadened at the level of the first tooth of the lower 

 margin and the latter appears a little concave at the base. 



Several specimens of Pal. carcinus from the Kutei river, 

 Borneo (Siboga Expedition), lie before me, amongst which are 

 several young ones, the youngest specimen being nearly 70 mm. 

 long, rostrum included. The rostrum of Pal. carcinus is narrower, 

 less broadened than in Pal. lamarrei, it reaches farther beyond 

 the antennal scales and the toothing is different ; of the twelve or 

 thirteen teeth of the upper margin the three first are placed on the 

 carapace, and there is no long smooth interspace as in Pal. lamarrei, 

 though the three or four teeth on the upturned part of the rostrum 

 are farther distant from each other than the proximal teeth ; the 

 lower margin, finally, presents also a larger number of teeth, eleven 

 or twelve, which reach to near the tip. 



The sixth segment of the abdomen (plate xix, fig. 5) is com- 

 paratively longer and broader in Pal. lamarrei than in Pal. carcinus. 

 In the specimen of the latter species, which is 70 mm. in length, 

 the carapace, rostrum excluded, being 12 mm. long, the sixth seg- 

 ment is 5*5 mm. long and 4*3 mm, broad in the middle ; in the 

 largest specimen of Pal. lamarrei^ which has a length of 38"5 mm,, 

 the carapace of which, without the rostrum, being 6'8 mm. long, the 

 sixth segment of the abdomen is 3 "9 mm. long and 2*4 mm. broad. 



The slender telson (fig. ^^d) apparently tapers less strongly 

 than that of Pal. carcinus (fig. 5a), but it reaches almost to the 



