PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



issued p^?(V>4. mIMb ^y '^^ 



SMITHSONIAN INSTITUTION 

 U. S. NATIONAL MUSEUM 



Vol. 101 Washington: 1951 No. 3272 



THE OCEANIC CRABS OF THE GENERA PLANES AND 



PACHYGRAPSUS 



By Fenner a. Chace, Jr. 



On September 17, 1492, at latitude approximately 28° N. and 

 longitude 37° W., Columbus and his crew, during their first voyage 

 to the NevT World, "saw much more weed appearing, like herbs from 

 rivers, in which they found a live crab, which the Admiral kept. He 

 says that these crabs are certain signs of land . . . "(Markham, 1893, 

 p. 25). This is possibly the first recorded reference to oceanic crabs. 

 Whether it refers to Planes or to the larger swimming crab, Portunus 

 (Portunus) sayi (Gibbes), which is seldom found this far to the east, 

 may be open to question, but the smaller and commoner Planes is 

 frequently called Columbus's crab after this item in the discov- 

 erer's diary. 



Although these crabs must have been a source of wonder to mariners 

 on the high seas in the past as they are today, the first adequate 

 description of them did not appear until more than two centuries after 

 Columbus's voyage when Sloane (1725, p. 270, pi. 245, fig. 1) recorded 

 specimens from seaweed north of Jamaica. A short time later 

 Linnaeus (1747, p. 137, pi. 1, figs. 1, a-h) described a sunilar form, 

 which he had received from a Goteborg druggist and which was 

 reputed to have come from Cantou. This specimen, which Linnaeus 

 named Cancer cantonensis, may be the first record of the Pacific 

 Planes cyaneus. The Atlantic species, found "in Palgi Fuco natante," 

 was finally described under the name Cancer minutus by Linnaeus in 

 the tenth edition of "Systema Naturae" (1758, p. 625). Bowdich 

 (1825, p. 15, pi. 12, figs. 2, a-h) briefiy described and figured a crab 

 found on a floating log northeast of Madeira as Planes clypeatus. 



874803—51 1 65 



