ix, d, 4 Cowles: Palaemons of the Philippine Islands 353 



by Coutiere, 29 and I believe that large series of P. idae Heller 30 

 and P. rudis Heller 31 will show the same thing. The merus, 

 which is flattened dorsoventrally along the proximal part, be- 

 comes almost cylindrical in cross section and of greater diameter 

 at the distal part. As in other palaemons, the merus grows more 

 rapidly than the ischium. While Table II shows that there is 

 some variability in the proportion between the merus and ischium 

 when a series of specimens is arranged according to increasing 

 body length, it may also be seen that when the measurements for 

 young mature males are separated from the rest this variability 

 is much reduced. 



The description of the shape of the ischium given for the 

 largest male applies to specimens of all ages and sexes. 



The chelipeds of young specimens show spines on the palm 

 and anterior part of the carpus, but the "linear spaces" are not 

 distinguishable. The covering of spines increases as the animals 

 become larger, but it is not until they have reached about the 

 middle size that the spines become apparent on the fingers and 

 ischium. The "linear spaces" then show clearly. 



Third, fourth, and fifth legs. — The third legs are missing in 

 specimen la. One-quarter and two-fifths of the propodus extend 

 beyond the tip of the antennal scale in the fourth and fifth legs, 

 respectively. The measurements for the propodus of the fifth 

 leg are 0.16 millimeter in diameter at the middle and 7 milli- 

 meters in length. In No. 16 the third, fourth, and fifth legs ex- 

 tend with two-thirds, two-fifths, and one-fourth of the propodus, 

 respectively, beyond the antennal scale. The propodus of the 

 fifth leg is 0.7 millimeter in diameter at the middle and 17 milli- 

 meters in length. A large specimen measuring 133 millimeters 

 (not indicated in Table II) shows one-fourth of the propodus 

 of the third leg extending beyond the antennal scale. In this 

 specimen the dactylus of the fourth leg extends beyond the scale, 

 while in the fifth leg merely the tip of the dactylus overreaches 

 the scale. The propodus of this leg is 19 millimeters in length, 

 and 1 millimeter in diameter at its middle point. 



Telson. — The armature of the telson varies with the size, but 

 the difference may be due to wear. In a young female 47 

 millimeters long (Plate II fig. 21) the tip of the telson is long, 

 the externolateral spines are well developed, and the interno- 

 lateral spines are very long, with almost three-fourths of their 



""Ann. Sci. Nat., Zool. (1900), 11, 314. 



s " Sitzungsber. Akad. d. Wiss., math.-nat. Klasse, Wien (1862), 45, 416. 



sl Reise der Osterreichischen Frigatte Novara (1868), 2, 115. 



