CRAB GENERA PLANES AND PACHYGRAPSUS — CHACE 77 



The color in life of Pachygrapsus marinus has not been published. 

 The specimens from a Japanese mine which prompted this survey were 

 rather dark reddish brown a short time after preservation in alcohol. 



Carapace Length {mm.) 



Figure 6. — Scatter diagram showing the variation in the combined length of the three 

 terminal segments of the second walking leg in Planes minutus, Planes cyaneus, and 

 Pachygrapsus marinus. 



FOOD 



The only published record of the stomach contents of any of these 

 species is that of Miss Crane (1937, p. 78) based on a large ovigerous 

 female of Planes cyaneus taken from the tail of a green turtle. The 

 stomach of this specimen contained finely digested animal matter. 

 Miss Crane suggests the possibility that this food material might 

 represent the excrement of the turtle. Some support is given to this 

 theory by the fact that larger specimens of Planes are commonly 

 found around the tail and hind legs of turtles. Specimens living on 

 other objects, however, must be able to assimilate less digested food. 



DISTRIBUTION 



The relative abundance of these oceanic crabs is more or less depend- 

 ent upon the prevalence of flotsam or of floating or swimming organ- 

 isms to which the crabs may cling. They are therefore found far 

 more commonly on Sargassum in the Sargasso Sea area of the North 

 Atlantic than in any other part of the world. Records of their occur- 



