Station 



Depth 



D 5808 



27-43 



D 5738 



23-60 



D 5809 



21J-53 



D 5700 



17-19 



D 5827 



6-17 



1921 J Schhiitt: The Marine Decapod Crustacea of California 45 



Biological Survey of San Francisco Bay. — Pandalus danae was 

 found almost exclusively in the deeper portions of the middle bay, the 

 region of greatest abundance being the outer central part of Golden 

 Gate where three (D 5738, 5808, 5809) of the six stations from which 

 it is recorded are located, and where 97 per cent of all the specimens 

 caught were taken. The other three stations (D 5700, 5827, 5828) 

 were made, one off Sausalito, one just to the westward of Alcatraz, 

 and the third in mid-channel off the southern end of the east side of 

 Angel Island (plate 5). 



A summary of the above stations indicates quite a close correspon- 

 dence between the depth, character of bottom, and the number of 

 specimens obtained: 



Number of 

 Character of bottom specimens 



Coarse sand, gravel and stones, ranging up 



to 14 inches in length. 23 



Large rocks with very little coarse shelly 



sand. 3 



Coarse sand, gravel and stones. 3 



Sand, coarse and fine gravel, broken shells. 2 



Clean, coarse sand and gravel, stones of all 

 sizes up to width of hand and one-half 

 inch thick at beginning, and sand and fine 

 gravel and no stones at end of haul. 1 



D 5828 10-16 "Variegated mud, containing some sand and 



many shells at beginning, and sand and 

 fine gravel with some shell fragments and 

 living mollusks at end of haul. 1 



As no specimen was taken at a temperature exceeding 12.2° C and 

 none in a salinity less than 25.7 it is apparently the combination of 

 the effects of higher temperature, lower salinity, shoaler water 

 together with that of the character of the bottom which restricts the 

 range of Pandalus danae in the bay, except in the section from which 

 it is here recorded. 



This is graphically demonstrable on the temperature and salinity 

 curves figured by Sumner in his report upon the physical conditions 

 in the Bay (1914, figs. B and M) : The occurrence of this species far 

 north of the southern shore of Angel Island, or at most the head of 

 Raccoon Strait or south of Goat Island, would be restricted from 

 January to July (periods I, II, III, and VI of Sumner) by rapid 

 falling of the salinity below the minimum value, 25.7, established 

 above, and from February to October (periods I, II, III, and IV) by 

 the rise of temperature above 12.2° C. By the process of elimination 

 only the months of November and December (period V of Sumner) 



