104 Sketch of the Infusoria of the family Bacillaria. 
This is one of the most beautiful of the fresh-water infusoria, 
and excites great admiration in all who behold its elegant form 
and markings, under a good microscope. It oceurs in immense 
quantities in the mountain brooks around West Point, the bot- 
toms of which are literally covered in the first warm days of 
spring, with a ferruginous colored mucous matter, about one 
quarter of an inch thick, which, on examination by the micro- 
scope, proves to be filled with millions and millions of these 
exquisitely beautiful siliceous bodies. Every submerged stone, 
twig, and spear of grass, is enveloped by them, and the waving 
plume-like appearance of a filamentous body covered in this way, 
is often very elegant. 
The spiral or helicoidal form of the chains is not easily per- 
ceived, unless the chains are thrown on edge, (as in fig. 42, b.) 
This i is easily effected with Chevalier’s compressor. 
- Alcohol completely dissolves the endochrome of this species, 
and the solution when evaporated, leaves a greenish resinous 
mass. ‘I'he frustules, after the action of alcohol, are as colorless 
as glass, and resist the action of fire and nitric acid. 
End of the Naviculacee. 
Explanation of the figures of Plate 2.—The figures which ‘aecom- 
pany this memoir, were all drawn by the aid of a camera lucida, and 
to the same scale as was used in the plates of the first part of this 
sketch. That scale is shown in fig. 15, which represents +4%ths of a 
millimetre, magnified equally with the drawings. In the sketches, a 
represents the side of the animal usually seen, ), the other side. 
Fig. 1. Pyxidicula operculata, fossil from Manchester, Mass,—flu- 
viatile. 
Fig. 1. a. Sain 1 ? fossil from Massachusetts. = 
Fig. 2. a, b. Pyxidicula ? Fossil in infusorial stratum at Richmond, 
Virginia 
Fig. 3. Gaillonella moniliformis, recent, m 
Fig. 4. 4a. meepscisinys —— geen Havin at ¢ is — a 
globular joint. 
Fig. 4. 6. Gaillonella aurichalcea ? recent, fluviatile. ve 
Fig. 5. Gaillonella distans, recent and fossil, fluviatile. » 
Fig. 6. a, b. Gaillonella varians, recent and fossil, fluviatile. 
Fig. 7. a, b. Gaillonella suleata. Fossil at Richmond, Va., recent, 
7 Stonington, Conn. selnintthaplntesionmpuied of 9m 
individuals ; 6, base of one of the joints... 
Fig. 8. Gaillonella? ——. 5 Hespeni, leschich wutec.of.tiiooa River 
at West Point. 
