4i8 Miscellaneous. 
sible, owing to the ruptures which take place in its mesenteroid 
folds. The insensibility produced by water charged with carbonic 
acid enables chromic acid to act fatally upon the animal without 
causing contractions and lesions. When thus: treated its internal 
organization differs considerably from that of all known Zoantharia, 
including Cerzanthus, which hitherto presented the most exceptional 
structure. 
Twelve perforated mesenteroid folds at the level of the cesophagus, 
Two of these folds, close together, instead of detaching themselves 
from the lower margin of the cesophagus, and floating freely in the 
general cavity, attach themselves to a gutter-like organ, the two 
margins of which are approximated. This gutter commences on one 
of the sides of the peristome, appearing externally as a papilliform 
lip, and terminates in the general cavity not far from an orifice, 
analogous to that of Cerianthus, which the animal possesses at its 
lower extremity. Hight longitudinal muscular cords project upon 
the inner wall, These are arranged in pairs, so that only four 
chambers out of the twelve possess them. These four chambers 
are placed unsymmetrically, one on each side of the organ above 
described, the other two opposite one another upon an axis perpen- 
dicular to that which would pass through the papilliform lp and 
the inferior orifice.—Comptes Rendus, March 24, 1884, p. 756. 
On a Cilio-flagelate Infusorian recently observed in Baltimore 
Drinking- Water. By C. 8. Dottey*. 
Having had my attention called to the presence of large numbers 
of a peculiar minute green organism in the water-supply of the 
Biological Laboratory, I became interested in identifying the same, 
and find it to be a species of Peridinium. So far as I have been 
able to ascertain, the only member of the family Peridiniide hitherto 
described as occurring in America is a salt-water species from the 
coast of South Carolina. After examining the specimens found 
here, very carefully, and comparing them with the specific descrip- 
tions given by Kent, I find that while they agree in most respects 
with Peridinium tabulatum, they also have many points in common 
with Peridiniwm apiculatum, though differing in several particulars 
from both. They would therefore seem to constitute an interme- 
diate species, or variety, if, in accordance with Stein, P. apiculatum 
be regarded as only a variety or older phase of P. tabulatum. The 
characters of our Baltimore specimen are as follows :—Body ovate 
or subglobose, as seen in dorsal or ventral aspect, with a convex 
dorsal and concave ventral surface as seen in lateral aspect ; cuirass 
composed of numerous polygonal facets, which in the row next to 
the equatorial furrow are separated by a clear space; the edges of 
these spaces as well as of the longitudinal and equatorial furrows 
are finely hispid. The remaining facets are closely united; all the 
facets have a very marked reticulate structure, with the exception 
* Abstract of some remarks before the University Scientific Association, 
February 6, 1884. 
