2 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



the single species P. exilipes, collected by the Albatross off Lower Cali- 

 fornia, in the Bay of Panama, and in the Galapagos Islands. As a result 

 of Velero III collecting, the range of this species has been extended to 

 Peru, while P. depressiuscula and P. excavata, represented by specimens 

 from Panama only, became known from numerous localities. In addition, 

 two species known only from the literature, P. hyponca and P. triangula, 

 were rediscovered, while still another species is made known in these 

 pages. 



Source of Materials 



The cruises of the Velero III from 1931 to 1941 and of the Velero IV 

 from 1949 to 1955, in which W. L. Schmitt, F. C. Ziesenhenne, and the 

 writer participated as carcinological collectors, have been the principal 

 source of the specimen material herein reported. However, the restriction 

 of the activities of the Allan Hancock Pacific expeditions to the territory 

 between San Francisco, California, and San Juan Bay, Peru, including 

 offshore islands, has necessitated drawing upon other sources for mate- 

 rial from north and south of these limits. Thus specimens from Alaska 

 and from Chile collected by the Albatross have been made available by 

 the U. S. National Museum, specimens from Galapagos and Juan Fer- 

 nandez Islands collected by the Hassler have been loaned by the Museum 

 of Comparative Zoology, and specimens from the recent Lund Uni- 

 versity Chile Expedition collected by professors E. Dahl and H. Bratt- 

 strom have been made available in advance of publication in the official 

 expedition reports. 



Supplementing Velero III material are collections from Peru obtained 

 by W. L. Schmitt while traveling under a Walter Rathbone Bacon 

 Fellowship of the Smithsonian Institution in 1926; from Ecuador by 

 R. Paessler in 1895 (courtesy Hamburg Museum) ; from Panama by 

 students of Elinor D. Robson in 1939; from Acapulco, Mexico, by C. L. 

 Hubbs in 1946 and E. Y. Dawson in 1947; and from the Gulf of Cali- 

 fornia by S. A. Glassell in 1940, by C. L. Hubbs (J. Rodriguez, collec- 

 tor) in 1947, by B. W. Halstead in 1949, and by W. N. Smith, II, in 

 1951. From the west coast of Lower California are specimens from San 

 Ignacio Lagoon collected by M. W. Johnson in 1950, from Scammon 

 Lagoon, Cedros Island, and Guadalupe Island by M. W. Williams in 

 1946, and from Guadalupe Island by C. L. Hubbs in 1946 and 1950. 



From the southern California-Channel Islands area are early collec- 

 tions of the Anton Dohrn made by A. B. Ulrey, P. L. Greeley, P. S. 

 Barnhart, and Elmer Higgins, dating back to the Venice Marine Labora- 



