DIATOMACE 161 
any alga growing between tide-marks may be washed by fresh water during 
heavy rains at low tide. 
The stand of any given alga may be pure over several square centimeters, a 
few decimeters, or, in some species, over some square meters. The vast majority 
of species, however, are mingled more or less abundantly with others, or occur 
sparsely, or even rarely as individuals, attached or free, often with no others of 
their kind within a distance of many meters. The latter is often true, e. g., of 
Agardhiella, Gracilaria, Porphyra, etc. Where but one or a few collections of 
a species have been made, and all at one level, this level is given under “ upper 
limit.” 
DIATOMACE. 
Besides the diatoms mentioned in Table G, a number of other species were 
identified by Dr. Albert Mann, in collections made on November 30, 1912, from 
the 3-foot level on two stakes in the middle of the harbor and from shells in the 
Inlet near the 1-foot level. They were not sought elsewhere and therefore their 
general distribution can not be given, as their colonies are not large enough to 
be conspicuous among the other alge of their habitats. The following include 
all the diatoms thus far identified from the Inner Harbor: 
Achnanthes brevipes Ag. Navicula alternans Schum. 
hauckii Grun. grevillei (Ag.) Cleve. 
longipes Ag. Kennedyi W. S. 
Actinoptychus splendens (Shad.) lyra Ebr. 
Ralfs. marina Ralfs. 
Amphora eulensteinii Grun. smithii Breb. 
Biddulphia aurita ,Lyngb.) Bred. Nitzschia acuminata W. S. Grun. 
Cocconeis scutellum Ehrb. longissima (Breb.) Ralfs. 
Coscinodiscus asteromphalus Ehrb. panduriformis (Greg.) 
decrescens Grun. Grun. 
excentricus Ehrb. paradoxa (Gmel.) Grun. 
radiatus Ehrb. sigma W. S. 
Cyclotella striata (Kg.) Grun. Pleurosigma angulatum W. S. 
Fragillaria brevistriata Grun. balticum W. S. 
Fragillaria sp. distortum W. S. 
Gomphonema curvatum Kg. intermedium W. S. 
Grammatophora marina Kg. Podosira subtilis (Bail) Mann. 
Licmophora tincta (Ag.) Grun. Synedra affinis. 
Lithodesmium undulatum Ehrb. 
Melosira borrei Grev. 
nummuloides (Bory.) Ag. 
