130 Rhodora [AucUsT - 
At Branford I find Ditylum Brightwellii (West) Grun.; the draw- 
ings in books show this with long central spine with abrupt termination, 
without finish; the Branford specimens have a longer spine terminating 
in a knob or ball, which indicates that the specimens from which the 
figures were made were broken. Nitzschia scalaris (Ehrenb.) W. Sm. 
grows abundantly in the brackish water of many of the pond holes 
of the salt marshes. Pond’s Point at Milford is a rounded projection 
where the southward trend of the shore changes abruptly to west. 
'The beach is composed of large cobblestones and boulders upon a 
coarse gravel. On its southern margin is visible at low tide a bank 
of fossil mud, which is firm enough to resist the action of the waves, 
and is being gradually uncovered as the mass of stones is driven back 
by storms. A stratum near the upper part of this bank is very rich 
in diatoms, showing an unusual combination of marine and brackish 
water forms of more than one hundred species. Coscinodiscus, 
Actinoptychus, Triceratium, Amphitetras, Eupodiscus, with a dozen 
species of Pleurosigma occur, while the abundance of the brackish 
water form of Surirella striatula and Navicula permagna, with Scolio- 
pleura, Amphora, Amphiprora and Nitzschia scalaris (Ehrenb.) W. Sm. 
show this mud to have once formed the bottom of a pond hole in the 
marsh; the fresh water spring that fed it still flows over it, and can be 
seen at low tide. The pressure of the great bank of stones which 
rested upon it during the time it was being driven over by the sea has 
crushed to fragments most of the delicate species, but enough remain 
to show conclusively its character. The marine species mentioned 
above can be found generally in deep water all along the Connecticut 
shore, while the different varieties of Navicula lyra Ehrenb. and the 
Pleurosigmas are most abundant in shallow water. I have P. inter- 
medium W. Sm. abundant in the deep water of Clinton, and the very 
rare Navicula Lewisiana Grev. in shallow water at Bridgeport. P. 
balticum is the most abundant species of the genus, and has many 
varieties, the largest being found in the salt marshes, the normal type 
in coves and bays, and the smallest in deep water. P. affine Grun. 
is the most universally distributed being found everywhere along the 
shore but not generally in great abundance. It is very often mistaken 
for P. angulatum W. Sm., although striation is very different. P. 
angulatum is frequent but local. A ditch in the Quinnipiac marshes 
through which flows at low tide a strong stream of nearly fresh water 
is carpeted with a dense growth of Biddulphia levis Ehrenb., and near 
