DECAPOD CRUSTACEANS FROM THE PANAMA 



REGION. 



By Mart J. Rathbun, 



Associate in Zoology, United States National Museum. 



INTRODUCTION. 



Fifty-eight species of Decapods are enumerated from the collec- 

 tions examined by the author. Three species described by other 

 authors are inserted in systematic order, thus making the list com- 

 plete to date for the Panama region. All the available material 

 in the United States National Museum from Panama and Costa Rica 

 is included; it ranges in age from the Oligocene (Culebra formation) 

 to the Pleistocene. 



In the list of stations and the table of distribution the data relat- 

 ing to Cirripedia from Dr. H. A. Pilsbry's report are included for 

 convenience of reference. 



The literature on Panama Tertiary Decapods is so scanty that it 

 is not surprising that nearly all of the forms now examined prove to 

 be new. Six species previously described from living forms are here 

 recorded from the Pleistocene (4 species) or the Pliocene (2 spe- 

 cies). Thirty-nine species are described as new, three are types of 

 new genera, and one of these is the type of a new family, the Ga- 

 tuniidae. This is an extremely large and massive crab and combines 

 the characters of the well-known Recent families, the Cancridae and 

 the Portunidae. The most remarkable occurrence is that of a mem- 

 ber of the Hexapodinae, that subfamily of the Goneplacidae in which 

 the legs of the last pair are wanting. This is a small group of Recent 

 crabs containing 5 genera and 8 species and is strictly Indo-Pacific. 

 The species from the Oligocene of Panama is the first one observed 

 in a fossil state. Many other genera dealt with in this report have 

 never before been found fossil. Such are Pachycheles, Petrolisthes, 

 Aosius, Hepatus, Mursia, Leucosilia, Euphylax, Heteractaea, Eury- 

 tium, Euryplax, and Cardisoma. 



As in all large collections of fossil crustaceans there are a number 

 of fragments whose position is problematic. Some of these can be 

 determined as to genera, others as to family only. 



83700—18— Bull. 103 9 123 



