THE OXYSTOMATOUS AND ALLIED CRABS OF 



AMERICA 



By Mary J. Rathbun 



Associate in Zoology, United States National Museum 



INTRODUCTION 



This volume is the fourth of a series of handbooks on American 

 crabs; the others are United States National Museum Bulletins 97, 

 129, and 152, on the grapsoid, spider, and cancroid crabs of America, 

 respectively. The introductory remarks in those bulletins relating 

 to sources of material, special researches, acknowledgments, and glos- 

 sary of terms apply to the present work also. 



In recent years the most fruitful expeditions, so far as collecting 

 American crabs is concerned, were those of the Velero III on the Pacific 

 coast, sponsored by Capt. G. Allan Hancock.^ In consequence, 16 

 new species or subspecies have been added to the groups here de- 

 scribed. Various stops were made in Mexico, Costa Rica, Panama, 

 Ecuador, Peru, and the Galapagos Islands, where Crustacea were 

 collected by Dr. W. L. Schmitt, Dr. C. M. Eraser, Dr. H. W. Manter, 

 Dr. W. R. Taylor, John Garth, and Fred Ziesenhenne. Dredging was 

 carried to a depth of 150 fathoms. New Pacific forms were obtained 

 by Steve A. Glassell and Herbert N. Lowe, especially at the head of 

 the Gulf of California, which, it appears, has developed a fauna of its 

 OMU. We have also benefited through the courtesy of the California 

 Academy of Sciences, which has loaned material obtained by the 

 Crocker expedition on the Zaca. Dr. Manuel Valerio, of San Jose, 

 has from time to time added to our knowledge of the Costa Rican 

 fauna. 



The Museum also has been enriched by vast collections of crabs 

 from South America obtained by Dr. Waldo L. Schmitt in the course 

 of two extended series of explorations in South American waters 

 under the auspices of the Walter Rathbone Bacon scholarship. 

 Besides the material collected, Dr. Schmitt was able to arrange 

 advantageous exchanges with various South American museums and 

 when that was not feasible to borrow specimens for study. In this 

 way many gaps in the National Museum collections were filled, both 

 as to species and numbers, and our knowledge of the fauna greatly 

 increased. 



' We are indebted to Captain Hancock for permission to publish these records in advance of the formal 

 publication of the results of the expeditions. 



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