88 Sketch of: the Infusoria of the family Bacillaria. 
Art. X.—A Sketch of the Infusoria, of the family Bacillaria, 
with some account of the most interesting species which have 
_been found in a recent or fossil state in the United States; by =. 
J. W. Batvey, Professor of Chemistry, Mineralogy, and Geol- — 
ogy, in the United States Military Academy. 
Parr II.* 
Havine given in the preceding part of this memoir, some ac- 
count of those Bacillariae which belong to the section Desmidi- 
acea, I continue the subject in the present part, by describing he oe 
Bacillariae of the section Naviculacea. — ote se 
As all the species referred to this section have siliceous cov- 
erings, they often occur in a fossil state, and hence their study is 
of peculiar interest to the geologist. In beauty of form and ele- 
gance of structure, they will bear comparison with almost any clas 
of eegces beings. 
Secr. If. NAVICULACEA. 
Pecrarcas 
Free, carapace simple, bivalve (siliceous) <uvain globular, 
(may be compared to a Gaillonella with perfect spontaneous divi- 
sion or without division. 
1. Pyxidicula operculata. (P\. 2, fig. land 1a.) Body spherical, 
divisible into two HE WNAPHOT CG: carapace hyaline, internal organs green- 
ish yellow, zig to zy line. 
I have seen hemispheres, probably derived fen this. species, 
among fossil infusoria from Manchester, Mass., 
2. Pyzidicula globata. 'This name has been given to Me: bodies 
found in flint. Beautiful figures of them by peer will be found in 
Pritchard’s Hist. Infusoria, pl. 12, figs. 506 to 509. It is now suspect- 
ed that these bodies are the gemmules of sponges, as the ramified tubes 
_ of sponge are often found preserved in the same pieces of flint. ° 
“8. Pyvidicula? (PI. 2, fig. 2, a,b.) The spheroidal bodies repre- 
poe by these figures, occur in the weiter’ infusorial stratum discovered 
- * Since the second part of this memoir: was ready for the press; - pare received 
poe availed myself of the. ‘onportunity. 10. introduce here  aaauagial pie pam 
facts which it contains.. Many of these facts will Nii siti in the form of notes, 
as tine dost a Soler peaed them in this nee eae 
form, 
