66 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



There is little doubt that Bowdich's species is conspecific with that 

 described earlier by Linnaeus, and the combination Planes minutus 

 is now generally accepted for the Atlantic species, despite repeated 

 attempts to substitute Nautilograpsus H. Milne-Edwards (1837, 

 p. 90) for Planes. 



As specimens of Planes trickled into collections from all parts of the 

 world in the early part of the nineteenth century, there was a natural 

 tendency to propose new names for varieties from widely separated 

 localities. A dozen different specific names were applied to these 

 crabs between 1775 and 1858. Thereafter the acquisition of larger 

 series of specimens served to illustrate the variability of these forms. 

 All the post-Linnaean names were subsequently synonymized with P. 

 minutus, and no additional ones were proposed except Planes marinus 

 Rathbun (1914, p. 120). The validity of even that species became 

 more and more questionable as time passed without additional speci- 

 mens being found. 



It was the rediscovery of that form that led to the present study. 

 In December 1947 four crabs were found among marine organisms 

 attached to a derelict Japanese mine that drifted ashore at Lincoln 

 Beach, Oreg. These proved to be the species described by Dr. 

 Rathbun and not reliably reported since her record of the type series 

 taken in the Pacific Ocean west of Baja California. Search of the 

 uncataloged collections in the U. S. National Aluseum revealed two 

 more specimens of this species, these from the Hawaiian Islands. A 

 subsequent query addressed to Dr. C. H. Edmondson at the Bernice 

 P. Bishop Museum in Honolulu led to the discovery of several lots 

 in that institution. A comparison of this form w4th specimens of 

 Planes minutus indicates that the two are generically as weU as spe- 

 cifically distinct and that there are at least two species of Planes s. s., 

 one found in the Atlantic and one in the Pacific. 



No attempt is made here to delimit these oceanic forms completely 

 either taxonomically or geographically. Additional material from 

 critical areas and "hosts" must be studied before this can be done. 

 It has been my aim to bring together as many of the scattered refer- 

 ences to these species as possible in the hope that workers elsewhere 

 may be encouraged to re-examine material at their disposal or to 

 collect specimens from other areas with a view to verifying or modify- 

 ing the conclusions outlined here. A species believed to be identical 

 and common in all the warmer seas of the world soon loses its interest ; 

 collectors fail to take the trouble to preserve specimens w^hen they are 

 found, and museum workers neglect to examine critically those that 

 are received. If this trend can be reversed as far as these crabs are 

 concerned, it is not unlikely that interesting findings related to specia- 

 tion and zoogeography may be forthcoming. 



