1921] Schmitt: 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 
Station Depth Character of bottom specimens 
D 5808 27-43 Coarse sand, gravel and stones, ranging up 
to 14 inches in length. 23 
D 5738 23-60 Large rocks with very little coarse shelly 
sand. 3 
D 5809 213-53 Coarse sand, gravel and stones. 3 
D 5700 17-19 Sand, coarse and fine gravel, broken shells. 2 
D 5827 6-17 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. il 
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) 
