100 = Sketch of the Infusoria of the family Bacillaria. 
Eunorta. 
Free, single or binary, carapace simple, bivalve or multivalve 
(siliceous) prismatic, four openings on the same side, two at each 
end, ventral side flattened, back conver and often dentate, never 
catenate by perfect spontaneous division. 
1. Eunotia areus. (Pl. 2, fig. 26, a,b.) Striate, carapace semi- 
lanceolate, elongated, two terminal knobs arcuate, 11 striz in +45 line. 
hrenberg mentions #’. arcus as occurring among fossil infu- 
soria from West Point. I presume that our figure, which rep- 
resents a form very common both in the recent and fossil state in 
the United States, belongs to this species. 
2. Eunotia diodon. (Pl. 2, fig. 29.) Striate, carapace elongated, 
ventral side flattened, slightly bidentate at the middle of the back, 19 
striee in yy line, gy to zy line 
Hab. West Point, fide Bliretibers: Probably the same as fig. 
29, which is common both recent and fossil at West Point, and 
‘elsewhere in the United States. 
3. Eunotia tetraodon. (Pl. 2, fig. 31.)  Striate, carapace seml- 
lunar, short, flattened or concave on the ventral side, four rounded teeth 
on the convex back, 28 strie in +}, line, gis to zy line. 
Common among fossil infusoria from Manchester, Mass., a 
West Point, N. Y. The ay species occurs at West Point. | 
4. Eunotia pentodon. (Pl. 2, fig. 32.) Striate, gi aa semi-lu- 
nar, short, five teeth on the convex back, 23 strie in +3, line. 
Fossil at Manchester, Mass. Living at West Point. 
5. Eunotia serra. (PI. 2, fig. 33.) Striate, carapace linear, aligaty 
curved, twelve to thirteen rounded teeth on the convex back, 19 trie 
in shu | line, A; to »y of a line. 
' figure is from specimens found fossil in Massachusetts. J 
have also received it from various other localities. “ 
I strongly suspect that the number of the teeth on the back of 
the four last described species of Eunotia, is liable to variation, 
and that the number of species has in consequence been made too 
great. See remarks in Final Report on Geology of Massachu- 
setts, Vol. II, p. 310, et seq. 
6. Eunotia (PL. 2, fig. 27, a, b.) This species was found 
in water from a brackish ditch in New Jersey, which was sent to me 
for examination by Dr. Torrey. It is concave on one side, convex on 
the other, Pi en ond widened pases in eae 
It is also minutely striate, — 
