ix, d, 4 Cowles: Palaemons of the Philippine Islands 385 



chelipeds are olive to a very dark blue, and show in places brown 

 mottled markings; and the walking legs show a mixture of 

 gray, blue, and brown. The color of the female is similar to 

 that of the male, except that the ventral edges of the pleura 

 are of a cream color. The colors are brighter in young than in 

 old individuals. 



Localities. — The collection contains 96 males and 1 female from 

 Port Galera, Mindoro, 1 male from the settling basin of the 

 Manila water works near San Juan del Monte, Luzon, Philip- 

 pine Islands, and 5 males from Guam, Mariana Islands. The 

 single specimen from the settling basin was collected by A. L. 

 Day, and those from Guam by R. C. McGregor. 



Palaemon jaroensis sp. nov. Plate III, figs. 8 and Sa-k. 



The work of Coutiere 40a on Palaemon lepidactylus Hilgendorf 

 and that of von Martens 41 on Palaemon grandimanus Randall 

 indicate that there may be striking differences in the shape and 

 proportion of the chela in a given species. The variability, 

 especially of the former species, renders it difficult to determine 

 whether or not one is dealing with a new species when examining 

 specimens which are quite similar in certain respects to Palae- 

 mon lepidactylus, but which come from new localities. 



The individuals of one series of specimens in our collection, 

 although not showing much variability, remind one of Palaemon 

 lepidactylus Hilgendorf. 42 After a careful examination I have 

 decided that they belong to a new and distinct species which is 

 closely related to Palaemon placidus de Man, 43 Palaemon hilgen- 

 dorfi H. Coutiere, and Palaemon lepidactylus Hilgendorf. This 

 species to which I have given the name Palaemon jaroensis is 

 represented in our collection by 23 specimens, of which 6 males 

 and 2 females are perfect so far as the chelipeds are concerned. 

 While there is considerable difference between the chelipeds of 

 the females and those of the males, this is probably sexual. 

 There is but little variability in the shape, proportions, and other 

 characteristics of the large cheliped of the male specimens, and 

 the same is true of the small cheliped, but there is a constant 

 difference in the proportional length of the segments of the large 

 cheliped when compared with those of the small cheliped of the 

 same individual. 



408 Ann. Sci. Nat., Zool. (1900), 11, 272. 

 "Arch. f. Naturgesch. (1868), 34, 45. 



" Monatsber. Preussischen Akad. d. Wissensch. Berlin (1879), 838. 

 43 Zoologische Ergebnisse einer Reise in Niederlandisch Ost-Indien 

 (1892), 2, 483. 



