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MARINE AND ESTUARINE DIATOMS. 
EXPLANATION OF TERMS. 
Frustule , one complete diatom cell. Front view , the aspect looking at the 
connecting membrane. Side view, looking at a valve. Valve, one side of cell, 
connecte 1 w'ith its fellow by the connecting membrane. Strife, lines of dots. 
Costce, ribs. Nodules, swellings at centre or extremities. Median line, central 
longitudinal space, destitute of striae. Stauros, a lateral expansion of median 
line to form a cross. Stipe, a stalk or pedicel, found in attached species. Keel, 
a line of prominences or projections. Awns, long and sharp processes. Plankton 
free, floating microscopic forms of life, plant or animal. Bacillar, rod like. 
Arcuate, bowed. Flabellate, in fan-like clusters. Cuneate, wedge-like. Sigmoid. 
like the letter S. Annulate, ringed. Septa, partitions. Calyptriform, like a cap, 
ACNANTHES. 
Acnanthes. Frustules bent, the upper surface convex, the lower concave. 
Solitary or aggregate, attached to a stipe, which may be long or short. 
Valves striate, unsymmetrical, the lower with a longitudinal or trans- 
verse line. Central and terminal nodules. 
A. longipes Ag. Very abundant in Miramichi Bay, Pasfeamaquoddy Bay 
and Grand Manan (rare). (Plate 1, Fig. 1.) 
A. brevipes Ag. 
A. subsessilis K. Kennebecasis. Rare. 
Actinoptychus. Frustules free or adherent, disciform. Valves plane or 
slightly convex, cellular, undulated, with conspicuous central nodule 
and radiating lines, dividing the surface into triangular segments. 
A. undulatus Kiitz. Common about Passamaquoddy Bay, St. John and 
St. Martins. Typically marine. (Plate 1, Fig. 2.) 
AMPHIPRORA. 
Amphiprora. Frustules, free, simple, in front view constricted in the middle; 
valves convex, with a longitudinal wing or keel, and central or terminal 
nodules. Striae, when present, transverse. 
A. alata Kiitz. Rothesay, St. Martins, Passamaquoddy. 
AMPHORA. 
Amphora. Frustules free, or adherent. Valves cymbiform; lateral view 
lunate or arcuate, with central marginal nodule. 
A. ovalis. (Plate 1. Fig. 3.) 
AMPHIPLEURA. 
Amphipleura. Frustules free, linear or sigmoid. Valves with longitudinal 
ridges. 
A. sigmoidea W. Sm. Rothesay, St. Martins. 
