NO. 3536 DECAPOD CRUSTACEANS— CHACE 647 



Remarks: Dell (1963) noted that this species has natatory fringes 

 on the walking legs, just as do the other two species of Planes. The 

 specimens that were available for my earlier study (Chace, 1951) were 

 so worn that this fringe was reduced to stift' bristles at most. All of 

 the St. Helena specmiens have well-developed natatory fringes. On 

 the basis of this character and the form of the gonopods, it seems best 

 to return the species to the genus to which it was originally assigned 

 by Rathbun and to minmiize the importance of the shape of the cara- 

 pace and chelipeds, which led me to transfer it to Pachygrapsus. 



Distribution: At sea, west of Baja California, Mexico; coast of 

 Orecron (from Japanese mine washed ashore); at sea, southwest of 

 Van'couver Island, British Columbia (from netting and barnacles on 

 large Japanese glass float) ; windward shores of Oahu, Hawan; Eastern 

 Bay of Plenty, New Zealand (among stalked barnacles on Japanese 

 glass float) ; St. Helena (first Atlantic record) . This species is probably 

 more common on floating objects than the rather sparse records would 

 indicate. 



Subfamily Plagusiinae 



Plagusia depressa (Fabricius) 



Cancer depresst/s Fabricius, 1775, p. 406. 



Plagusia depressa.-Cnnningh^m, 1910, p. 122.-Monod, 1956, p. 455, figs. 



614-617. 

 Plagusia.— Colman, 1946, p. 271. 



Material: Off Rupert's Bay ; buoy cable; 0-75 meters; Jan. 17, 1958; 

 1 female.— Same; buoy ; 0-2 meters; Feb. 2, 1959 ; 17 males, 16 females 

 (3 ovigerous), 2 juveniles.— James Bay, West Rocks; Dec. 21, 1959; 

 fragments of cast shell of 1 male.— Off Rupert's Bay; buoy and cable; 

 0-75 meters; Mar. 18, 1960; 34 males, 20 females (1 ovigerous), 10 

 juveniles.— Same; Apr. 5, 1962; 1 male.— Same; buoy; 0-2 meters; 

 Feb. 11, 1963; 9 males, 11 females (5 ovigerous), 1 fragmentary speci- 

 men.— James Bay; collected by skindiver; February 1964; 4 juve- 

 niles.— Same; April 1964; 11 males, 12 females (2 ovigerous). 



Measurements: Carapace lengths of males in midhne, 9.2-41.5 

 mm.; of females without eggs, 9.0-23.6 mm.; of ovigerous females, 

 19.1-33.3 mm.; of juveniles, 5.7-9.2 mm. 



Remarks: Most of the St. Helena specimens are immature, with 

 carapace lengths of less than 20 mm. (at about which size the female 

 abdomen attains its fuU breadth). The largest specimen, except for 

 the cast shell from James Bay, is a male with a carapace length of 

 35.2 mm. Nearly half (57 of 122) of the specimens from the buoy and 

 cable off Rupert's Bay have carapaces less than 14 mm. long 

 (with triangular female abdomens), but only 12 of these were so 

 small (carapace lengths of less than about 9 mm.) as to be sexuaUy 

 indeterminable. 



