BIOLOGICAL STUDY OF CHESAPEAKE BAY WATERS 
353 
While catches of Neomysis americana in tow nets can never give a very satis- 
factory idea of the numbers present in Chesapeake Bay during different times of the 
year, since the individuals are not swarming in the water at all times but may be 
hidden among water plants, etc., yet the catches in the bottom net (nonclosing), 
which was attached to a small beam trawl and towed for 10 minutes, are of interest. 
During the January cruise the numbers brought to the surface were large — for example 
in round numbers, 1,000 at area F, 8,000 at area B, 5,500 at area Q, 7,000 at area J 
and 40 at area R'. No bottom hauls were made north of area R', but the vertical nets 
showed the presence of Neomysis as far north as area W off Bloody Point. A similar 
distribution was found when the March cruise was taken, but the numbers were 
smaller. Very small catches (ordinarily less than 100 specimens) were obtained on 
the May, July, and August cruises except on one occasion at area G during the July 
cruise, when 4,000 specimens were caught. A few specimens were captured on the 
100-fathom line just off the mouth of the bay during the August cruise. The counts 
were larger when the October and December cruises were taken than during the 
summer. 
In January and March, 1920, the specimens collected were mostly of large size, 
but on the May cruise only small individuals were found. During the July, August, 
October, and December cruises the towings brought to light somewhat larger speci- 
mens. On the January and March-April cruises (1921) mostly very large specimens 
were caught, while on the May-June cruise (1921) the specimens were mostly small 
again as during the cruises of about the same periods in 1920. 
These size relations are in keeping with the observation of Fish (1925) for Woods 
Hole, that Neomysis americana breeds in the winter. In fact, eggs and young and 
large specimens with brood sacs were taken during the January, 1920, cruise. The 
great majority of the specimens were large; only a few were small, and these were 
evidently recently hatched and immature. The conditions found on the March 
cruise were similar to those just mentioned, but in the May catches the large individ- 
uals were scarce. Some of these, however, had brood sacs containing very young 
larvse. In the July towings the large specimens so characteristic of the earlier months 
of the year were not present, but on the other hand specimens of more than one-half 
the size of those large specimens (probably the partly grown young of the earlier 
months) made up the whole catch. Some of the specimens just mentioned had 
brood sacs filled with eggs, and there were a few larvse present. During the October 
cruise the conditions were much as in July — eggs and young larvse were found in the 
brood sacs and there were some very young specimens free from the parent. The 
material from the December cruise contained no individuals with eggs or with young, 
although in a few specimens the remains of a brood sac could be seen. The cruises of 
January, March-April, and May-June, 1921, showed the breeding conditions as on 
the January, March, and May cruises of 1920. 
These observations indicate then that breeding individuals are present through- 
out most of the year in Chesapeake Bay, a condition which was thought likely by 
Smith (1879) when he studied Neomysis farther north. 
It is evident from a study of large numbers of surface towings that Neomysis 
does not ordinarily frequent the surface waters in Chesapeake Bay during the day- 
time, but there is evidence to show that it may appear there in large numbers when 
the intensity of the light is low, even when there is a distinct stratification of the 
water and there is a large difference between the salinity of the surface and bottom 
