388 The Philippine Journal of Science 1914 



A thick growth of rather short hairs is present along the cutting 

 edge of both fingers, and as a result the teeth described above 

 are completely concealed. 



The much flattened palm (11.5 millimeters wide and 8.5 milli- 

 meters thick) is longer than the fingers, the proportion of the 

 length of the fingers to that of the palm being 1 :1.19 ; the slightly 

 flattened carpus which is smaller in diameter and shorter than 

 the palm equals the fingers in length; and the merus is shorter 

 than the carpus,* 5 a condition which seems to be characteristic 

 of Palaemon placidus, but not of Palaemon hilgendorfi or Palae- 

 mon lepidactylus. 



The smaller cheliped measures 65.5 millimeters in length, 

 and the distal end of the merus just reaches the tip of the 

 antennal scale. It is similar in appearance to the large cheliped, 

 but the relative lengths of the different segments are not the 

 same. As in the case of the large cheliped the fingers gape, 

 the mobile one curving rather sharply and the immobile one 

 being practically straight. The dentition of the fingers is similar 

 to that of the fingers of the large cheliped, except that the distal 

 series of teeth along the inner side of each finger is made up 

 of a smaller number of teeth and that there are 8 proximal 

 teeth on the immobile finger instead of 6. The cutting edge of 

 each finger is clothed with a heavy coat of short hairs which con- 

 ceals the teeth. 



The fingers (15.5 millimeters) are longer than the palm (14.5 

 millimeters), and this is true for the small cheliped of all the 

 male specimens. The palm is flattened, and measures, at its 

 widest point, 7.5 millimeters in width and 5 millimeters in thick- 

 ness. The carpus is slightly longer than the palm, and the same 

 is true for these 2 segments in the small cheliped of all the 

 male specimens. As in the large cheliped the merus is shorter 

 than the carpus. 



The impression one receives from comparing the large and 

 small chelipeds of the same individual is that the smaller is 

 merely a younger stage in the development of the larger, that 

 if the specimen had lived and molted the palm of the former 

 would have increased in length at a faster rate than the carpus, 

 and that finally the small cheliped would have assumed the form, 

 size, proportions, and general characteristics of the larger che- 

 liped. It is impossible to determine, however, with the specimens 



45 All the males of this species in our collection show a similar condition, 

 but in the females the carpus and merus are about equal, and it is probable 

 that the latter is true of young males. 



