62 TRUE CRABS OF MONTEREY BAY 



This is perhaps the most common crab on the southern part of the 

 bay where the shores are rocky. It is never found on sandy beaches, but 

 seems to prefer the rocks where it may be found running actively about 

 between or above tides and feeding on cast up fish or other refuse. 



General color in life a very dark red with a variable amount of 

 whitish, which is sometimes almost entirely absent and again gives to the 

 whole a light shade. A line of the light color is usually present in front 

 of each of the striae of the carapace, and spots in the intestinal and cardiac 

 regions. The ambulatory legs are similar in color to the carapace ; the 

 chelipeds are generally tan colored veined with red. The thin cuticle at 

 the joints is a livid green. 



In the series examined no marked variation was noted. 



Genus HEMIGRAPSUS (Dana). 



Hemigrapsus Dana, Proc. Acad. Nat. Sci. Phila., v, 247 and 250, 185 1. — Dana, Am. 

 Journ. Sci., (2) xii, 283, 1851 (Type — Hemigrapsus crassimanus Dana). 



Key to species. 

 a. Ambulatory legs smooth, hands with red spots, front sinuous. 



H. nudus 

 aa. Ambulatory legs hairy, hands without spots, front lobed. 



H. oregonensis 



Hemigrapsus nudus (Dana). 

 Plate XIV, fig. 42. 



Pseudograpsus nudus Dana, Proc. Acad. Nat. Sci. Phila., 249, 1851. 

 Brachynotus nudus Holmes, Occas. Papers Calif. Acad. Sci., vii, 81, 1900. 

 Hemigrapsus nudus Rathbun, H. A. E., x, 189, 1904. 



A very common crab found on rocky shores with Pachygrapsus 

 crassipes. Color in life a very dark purple marked with more or less 

 white or creamish. The chief of these markings occur in the H-shaped 

 depression in the center of the carapace and in the pits lying anterior to 

 it. Ambulatory legs similar to carapace; chelipeds lighter, marked with 

 numerous small spots of darker red. Under parts whitish. Color in 

 alcohol similar, fading only after a considerable time. The color of 

 adults is very uniform, young somewhat more variable. 



