356 The Philippine Journal of Science ww 



differs considerably from the specimens described by de Man 

 and by Coutiere. 



The specimens listed in Table III were all seen by me while 

 they were still alive. Judging from certain characteristic color 

 markings, especially the pattern on the chelipeds, which were 

 present in specimens of all sizes and sexes, one could not fail 

 to include them under one species. Even the young mature males 

 (Nos. 15 and 20) with the exceptionally long chelipeds showed 

 the characteristic markings. 



Notwithstanding the differences between our large males and 

 the smaller males described by de Man, I do not feel justified 

 in establishing a new species until larger collections of the Javan 

 form are made. 



While I have not been able to see any figures or specimens 

 of the American species, Palaemon acanthurus Wiegmann, 37 

 except Ortmann's 38 drawing of the telson which agrees well with 

 young individuals of this species, the descriptions indicate that 

 it is a larger form, although I believe our series does not include 

 the largest specimens to be found. The proportion of the palm 

 to the fingers in old males and the shape of the rostrum are 

 different, but the coat of felted hairs on the fingers of the males 

 is present in both. I believe that Palaemon acanthurus Wieg- 

 mann and the form under consideration are closely related, and 

 I should not be surprised if, when further collections of Palaemon 

 sundaicus from Java are made, older males with more mature 

 characters are brought to light which will ally the Javan species 

 closer to Palaemon acanthurus. 



Rostrum and antennal scales. — The position of the tip of the 

 rostrum with reference to the tip of the antennal scale does 

 not vary much in our specimens. In both males and females the 

 tip may be even with, extend slightly beyond, or fail slightly 

 to reach, the distal end of the scale. It is possible, however, 

 that in larger males the rostrum may not extend so far forward. 



Curvature and dental formula of rostrum. — There is little 

 difference in the shape of the rostrum in the males and females 

 of all ages. The distal third is turned upward somewhat, and 

 there is in nearly every case a gentle convexity over the eye. 

 Usually there are 3 rostral teeth on the carapace, the fourth 

 being over the edge of the orbit, and rarely are there 2 or 4 

 on the carapace. The rostral ridge divides the lateral surface 

 of the rostrum into an upper and a lower area which are of 



"Arch. f. Naturgesch. (1836), 1, 150. 



m Zool. Jahrb., Systematik (1891) 5, Tafel XLVII, Fig. 5. 



