804 THE AMERICAN NATURALIST. [VoL. XXXIII. 
short distance only by a continuation of the chitinous perisarc. 
Each hydranth is essentially a very long tube, consisting of 
two layers, the ectoderm and entoderm. It is of uniform 
diameter below, but somewhat swollen at the distal end below 
the circlet of tentacles. The latter are arranged in a single 
verticel and number from fifteen to thirty, or even thirty- 
five. There are usually between eighteen and twenty-five. 
The tentacles are solid, the entodermal core consisting of a 
single row of cells. Throughout the length there are stinging 
cells, but they are more 
abundant near the tips. The 
same applies to the hydranth 
body, in which the stinging 
cells are much more abun- 
dant around the hypostome. 
The tentacles are frequently 
bifid 
In their general features 
the reproductive hydranths 
A, (Fig. 2, (4) and (5)) are quite 
Fic. 5. — Longitudinal — of nearly mature similar to the nutritive, the 
radial Colt, iat», salah cu. dee dieca in the former 
tive cavity * Si eas ag of H feram being the somewhat smaller 
R size, the smaller numbers 
of tentacles, and the presence of a variable number of buds 
which develop into medusæ. In fully developed individuals the 
number of tentacles varies from six to fifteen, the usual number 
being eight to twelve. Like those of the nutritive hydranths, 
they are filiform, of uniform diameter, and arranged in a single 
circle. The reproductive buds vary in number from one to 
seven, the usual number being four or five. The presence of 
buds in various degrees of development in all colonies collected 
from July 8 to August 16, indicates that the breeding season 
extends at least through July and August. It may be that it 
begins earlier and ends later. When mature, the buds are set 
free from time to time as free-swimming medusæ. Though 
chiefly concerned with reproduction, these hydranths are also 
capable of taking food, at least sometimes. 
