SHRIMPS OF THE GENUS BETAEUS — HART 433 



The figures are drawn to three magnifications : scales A, B (two times 

 A), C (ten times A). The whole animal, the chelipeds, and chelae 

 are scale A; the dactyli, scale C; and the remainder, scale B. New 

 keys and comparative tables incorporating the new species are pre- 

 sented. In this aspect the work of L. B. Holthuis (1952) on two 

 species found in Chile has been very useful. 



In classification, emphasis in the past has been placed on the pro- 

 portions of the segments of the antennular peduncle, and on the size, 

 shape, and dentition of the large chelae. These features, however, 

 have been found to differ with age, sex, and extent of regeneration. 

 In this paper, therefore, an attempt is made to use as diagnosis those 

 characters that do not vary appreciably during the life of the 

 individual. 



Sexual dimorphism also is noted in this account. Differences due 

 to sex are most obvious in large males of B. longidactylus, in which 

 the chelipeds are much larger in relative proportion to the rest of the 

 body than in smaller males or in females. All the other species 

 dealt with here also show sexual dimorphism but only to a minor 

 extent such as stouter appendages and narrower pleura on the 

 abdomens of the males. 



Acknowledgments 



My thanks are due to Dr. Waldo L. Schmitt and Dr. Fenner A. 

 Chace, Jr., of the United States National Museum for the loan of 

 comparative material, for making comparisons with the type of B. 

 harrimani, and for much other help. In addition. Dr. Chace read the 

 manuscript and gave invaluable advice. The late Dr. Belle A. Stevens 

 was most helpful in the earl}^ stages of the study. I wish also to thank 

 both Dr. Paul L. Illg of the Department of Zoology, University of 

 Washington, and Mrs. G. E. MacGinitie, retired from Kerckhoff 

 Marine Laboratory, for much help and encouragement, as well as 

 for specimens. Thanks also are due to Mr. Keith W. Cox, California 

 Department of Fish and Game, who has given me specimens and 

 much useful data on Betaeus harfordi obtained in connection with 

 his work on Haliotis. 



For the use of material I am indebted to the following: Mr. T. H. 

 Butler and the Fisheries Research Board of Canada; Dr. Joel W. 

 Hedgpeth (Pacific Marine Station) ; Dr. Rolf Bolin and Dr. Donald 

 P. Abbott (Hopkins Marine Station) ; Dr. Olga Hartman (University 

 of Southern California, Allan Hancock Foundation) for the loan of 

 the late S. A. Glassell's collection; Dr. James E. Lynch (University 

 of Washington) for collections by Dr. John S. Laurie; and Dr. R. U. 

 Gooding of the University of Washington at the time. 



