34 



TRUE CRABS OF MONTEREY BAY 



Total length 



Width at posterior bran- 

 chial tubercle 



Width between margins of 



carapace 



Rostrum, notch to tip. ... 



tip to base of 



preocular spine 



greatest width . . 



Branchial tubercles. . 



Anterior median tubercle. . 

 Cardiac tubercle. . 



37 mm 39 mm. 



27 



27-5 

 4 



7 

 7 



Posterior prominent, 

 anterior a tubercu- 

 lated knob. 



Almost obsolete. 

 A smooth elevation 



27 



26 

 6 



10.5 

 9 



United in a heavy ridge 

 overhanging poster- 

 iorly the edge of car- 

 apace. 



Sharp and prominent. 



A hemispherical, tuber- 

 culated knob. 



The young males are smoother than the adults and have narrower 

 and more divergent horns to the rostrum, while the females have at times 

 carapaces which are little more than undulated. The anterior external 

 angle of the basal antennal joint is somewhat produced but seems hardly 

 to form a spine as stated by Holmes. The "two spines or teeth on the 

 outer margin" behind this are seldom prominent, the anterior being little 

 more than an undulation of the margin. 



This species is found from between tides to 20 fathoms, and like 

 most of the spider crabs is generally so overgrown with sponges and 

 other forms as to conceal the color. 



All of the egg-bearing females are dated June. 



Genus RHODIA Bell. 



Rhodia Bell, Proc. Zool. Soc. Lond., 169, 1835 J Trans. Zool. Soc. Lond., vol. ii, 43, 

 1841 (Type Rhodia pyriformis Bell). 



Rhodia parvifrons (Randall). 

 Plate VII, fig. 18. 



Herbstia parvifrons Randall, Journ. Acad. Nat. Sci. Phila., viii, 170, 1839. Holmes, 



Occas. Papers Calif. Acad. Sci., vii, 38, 1900. 



Herbstia (Herbsticlla) campacantha Holmes, op. cit. 37, and synonymy. 

 Rhodia parvifrons Rathbun, H. A. E., 175, 1904, and synonymy. 



Five specimens of this species have been obtained by the writer 

 during 1908, all from a large tide-pool just south of the Point Pinos 

 lighthouse. These agree well with Holmes's description except that the 



