6 TRUE CRABS OF MONTEREY BAY 



ly yield much to a more thorough use of the tangle than has yet been 

 attempted. 



The present work was begun at the Marine Laboratory during the 

 summer session of 1906, when J. N. Procter and the writer, working 

 under the direction of Dr. G. C. Price, made and indentified a consider- 

 able collection of Crustacea. It has been finished at Stanford University 

 under the guidance of Dr. H. Heath and Dr. W. K. Fisher, to whom as 

 well as to Dr. G. C. Price, the writer is greatly indebted. The material 

 upon which the work is based has been collected for the greater part by 

 the writer during the three summers of 1906, 1907 and 1908, but includes 

 as well the results of the collecting of numerous students at the Marine 

 Laboratory, among whom the manuscript of the keys has been in use 

 during the session of 1908, and all specimens in the University collection 

 known to have come from Monterey Bay. 



The writer wishes to express his obligations to W. F. Allen of Pacific 

 Grove for material, and especially to Miss M. J. Rathbun of the United 

 States National Museum for much kind assistance in determining speci- 

 mens and for the loan of material. 



There has been much excellent work done on the west American 

 Crustacea, and the writer is particularly indebted to the papers of S. J. 

 Holmes and Miss M. J. Rathbun. No attempt has been made to dupli- 

 cate the full descriptions of Holmes, attention being confined to the noting 

 of variations or other points of interest except in the case of a few species, 

 whose descriptions are incomplete or not easily accessible, and which have 

 been treated at some length. 



The writer has followed Borradaile (Annals and Magazine of 

 Natural History, Seventh series, vol. 19, p. 457) in the use of the sub- 

 orders Natantia and Reptantia instead of Macrura and Brachyura (or 

 Macrura, Anomura and Brachyura) and in the inclusion of the Dromiidae 

 with the Brachyura instead of with the Anomura. The keys to suborders 

 and tribes are taken from his paper with some modifications. In the 

 arrangement of families, though not of species. Miss Rathbun (Decapod 

 Crustaceans of the Northwest Coast of North America, Harriman Alaska 

 Expedition, vol. 10) has been followed. 



Fifty-two species are here treated. Of these, the occurence of forty- 

 three is well established, six rest on doubtful records and three more are 

 included because found in adjacent regions or for completeness. Of the 

 forty-three species thirty-six are represented in the collection at hand. 

 One new species is here described. The following lists set forth these 

 facts more clearly. 



