1921 1 Schmitt: The Marine Decapod Crustacea of California 295 



burrowing forms, which, though not found in company, were taken 

 only from sandy beaches: 



Emerita analog a was dug out of the beach skirting the Presidio, west of 

 Fort Point, and brought up in the seine both at Fort Baker and on 

 Angel Island. 



Upogcbia pugettensis was obtained both at Sausalito and at Tiburon; at 

 the latter place by means of the seine. 



The other five are all primarily inhabitants of rocky beaches : 



Oedignathus inermis, at Point Bonita. 



Petrolisthes cinctipes, at Sausalito, and along the Kichmond shore. 



Pagurus samuclis, along the Kichmond shore. 



P achy g rap sus crassipes, on the Presidio shore near Fort Point, at Point 



Bonita, at Sausalito, and on Eed Bock. 

 Hemigrapsus nudus, on the Presidio shore near Fort Point, at Point Bonita, 



at Sausalito, north of the Key Boute Pier, along the Bichmond shore, 



and on Bed Bock. 



The other sixteen bay species grouped on the basis of their dis- 

 tribution within the bay, arrange themselves as follows : 



a. Ten, restricted to the middle bay : 



Pandalus danae Crago munijtella 



Spirontocaris franciscana Epialtus productus 



Spirontocaris paludicola Cancer antennarius 



Spirontocaris trevirostris Pinnixa littoralis 



Spirontocaris taylori Scleroplax granulata 



b. One, found only in the middle and the lower bay. 



Cancer productus. 



c. Five, common to all three divisions of the bay : 



Callianassa longimana Pinnixa schmitti 



Pagurus hirsutiusculus Hemigrapsus oregonensis 



Pinnixa franciscana 



a. Excepting the first, third and ninth, seven of the ten species 

 found only in the middle bay, inclusive of shore stations, are re- 

 stricted wholly to that portion lying west of a line drawn across the 

 head of Raccoon Strait, and from Blunt Point on Angel Island to 

 the nearest point on the San Francisco shore. 



This limitation of range seems to be closely correlated with the 

 character of the bottom, which within that area is more or less hard, 

 rocky, gravelly, or sandy with very little if any admixture of mud, 

 exclusive, of course, of the muddy portion of Richardson Bay, where 

 only two hauls of the boat dredge were made and none of the strictly 

 middle bay species was found. 



