BIOLOGICAL STUDY OF CHESAPEAKE BAY WATERS 
313 
It is interesting to compare the species collected during 1915 and 1916 in Chesa- 
peake Bay with the species observed by Fish (1925) at Woods Hole during 1923, 
although in comparing the two it must be remembered that collections at Woods 
Hole were made largely at the surface. However, Fish has found that the water at 
Woods Hole is thoroughly mixed owing to currents. Those marine planktonic species 
in common for the two regions, following Fish’s grouping, are these: 
Fresh and brackish water forms: None. 
Semibottom forms: Actinoptychus undulatus, Hyalodiscus stelliger. 
Neritic, Arctic: None. 
Neritic, Northerly Temperate: Chaetoceras teres, Leptocylindrus danicus, Nitzschia 
longissima, Rhizosolenia setigera, Skeletonema costatum, Thalassiothrix nitzschioides. 
Neritic, Southerly Temperate: Bacteriastrum varians, Ceratulina bergonii, 
Ditylium brightwellii, Guinardia flaccida, Rhizosolenia calcar avis. 
Neritic, Tropical: Bellerochea malleus. 
Oceanic, Boreal Arctic : Chaetoceras decipiens, Rhizosolenia hebetata ver. semispina. 
Oceanic, Temperate: Rhizosolenia alata j. genuina (?), Rhizosolenia styliformis, 
Thalassiothrix jrauenjeldii. 
Oceanic, Tropical: None. 
Here again, as in the case of the Chesapeake diatoms, a survey of the complete 
list of species as given in Fish’s paper, with reference to the geographic groups in 
which they are usually placed, shows more temperate neritic forms than boreal arctic 
or tropical, and of these temperate forms the larger number belong to the southerly 
temperate neritic. The oceanic forms are much fewer in number than the neritic 
forms, a condition which is true of the Chesapeake collections. It should be noted, 
however, that the proportion of boreal arctic oceanic forms shows a considerable 
increase over what is found in Chesapeake Bay, and this is what should be expected. 
It is also in keeping with the fact that the colder currents from the northern regions 
which carry boreal arctic forms are of more importance in the latitude of Woods Hole 
than they are in the latitude of the mouth of Chesapeake Bay, where such currents 
have probably dipped below the Gulf Stream. 
A study of Bigelow’s (1914a, 1914b, 1915, 1917a) preliminary work on collec- 
tions made in the Gulf of Maine, Massachusetts Bay, and the coastal waters between 
Maine and the mouth of the Chesapeake Bay show the preponderance of temperate 
neritic forms as is the case for Chesapeake Bay and Woods Hole, while the boreal 
arctic forms have assumed considerable importance among the oceanic diatoms as 
at Woods Hole. 
Although Bailey’s (1917) collections in the Bay of Fundy were made at a little 
higher latitude than those of Bigelow, not so many boreal arctic forms were found, 
although they were fairly well represented. His records cover collections made from 
January to October, inclusive, 1916 (?). 
Still farther north the work of Gran (1919) in the Gulf of St. Lawrence and the 
oceanic regions outside of it shows the northerly forms replacing almost, if not entirely, 
the southerly forms. With the exception of four species which I have not been able 
to place with the literature at hand, the various species are grouped as follows : Arctic 
neritic, 9; boreal arctic neritic, 5; northerly temperate neritic, 3; arctic oceanic, 
1 (?); boreal arctic oceanic, 5. Gran’s collections were made during May, June and 
August, 1915. 
