256 Bulletin Vanderbilt Marine Museum, Vol. VII 



an evenly coloured light olivaceous green. The illustration is ap- 

 parently based on a female. 



Distribution : In addition to the above cited Chilean locali- 

 ties for the three sets of type material recorded, a series of spe- 

 cimens of this species were obtained by Dr. R. E. Coker, of the 

 United States Bureau of Fisheries, in Peru at Pacasmayo, Lima 

 market, in the Rimac below Lima, at Arequipo and Mollendo. 

 These specimens were deposited in the United States National 

 Museum. In her report on these. Miss M. J. Rathbun (1910) 

 also gives Ecuador in her distribution of the species, but fails 

 to list either specimens, or any authority for this more northern 

 locality. 



The reliably known distribution of Palaemon caementariu^ is 

 from northern Peru to southern Chile, where it is found rather 

 abundantly along the banks of freshwater rivers and their tribu- 

 taries, including irrigation ditches. 



Material examined: Eight specimens, four females, two of 

 which are ovigerous, and four males, collected in Callao, Peru, 

 1935, by the "Alva." 



Habitat: This was described by the Abbe Don Molina, in 

 1782, as follows : 



"Of the freshwater crabs, the most remarkable is that called 

 the mason (Caficer cementariu^) . It is about eight inches long, 

 of a brown colour striped with red ; the flesh is very white and 

 preferable to that of any other species of river or sea crab. They 

 are found in abundance in almost all the rivers and brooks, on 

 whose shores they build themselves, with clay, a small cylindri- 

 cal tenement, which rises six inches above the surface of the 

 ground, but admits the water, by means of a subterranean canal 

 extending to the bed of the river. They are readily caught by let- 

 ting down a basket or osier pot, with a piece of meat in it, into 

 the water." (From the English edition. History of Chile, 1809, 

 vol. I, p. 171, London). 



Technical description: This species, considered a great 

 delicacy by both white and Indian residents of western South 

 America, is a close congener of the later-described Palaemon 

 olfersi (Wiegmann) 1836, from the coasts of Brazil.* 



The present species is characterized by a short, thick cara- 



*Pa!acmon olfersi Wiegmann, Archiv. f. Naturg., 1836, Bd. II, pt. I, p. 150. 



