96 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [390] 
the Hydroids that occur on the piles of wharves, and on the under side 
of floating timber, is the Parypha crocea, (Plate XXXVI, fig. 274.) 
This species grows in great luxuriance upon the piles, especially in 
those harbors where the water is somewhat brackish. It forms large 
clusters of branching stems, often six inches or more in height, each of 
which is surmounted by a beautiful, flower-like, drooping head of a pink 
or bright red color. These heads are often broken off, or even volun- 
tarily cast off, when the animals are unhealthy, but new ones are soon 
reproduced, and, therefore, this does not seem to be a very serious acci- 
dent, though certainly a very inconvenient one, for the mouth, stomach, 
tentacles, and most other organs are all lost when these ‘“ heads” 
drop off. This species does not produce free-swimming meduse, but 
the buds, corresponding to those that develop into free meduse in many 
other cases, in this remain attached to the heads in drooping clusters, 
looking like loose clusters of light red grapes, in miniature. 
The buds produced by the hydroid-heads of one colony are either all 
males or females, and, while attached to the hydroid-heads, eggs or 
spermules are alaclopea within them; the eggs are fertilized and de- 
velop into young hydroids, which, when finally expelled, are provided 
with a circle of slender tentacles, and need only to attach themselves 
to some solid substance by the basal end of the body to become fixed, 
tubularian hydroids, similar to the old ones in many respects, though 
still very small and simple in structure. These young tubularians swim 
and crawl about for a time, and after attaching themselves they rap- 
idly grow larger and produce stolons from the base, from which buds 
arise that develop into forms like the first one; other buds are pro- 
duced from the sides of the stems, which also become. like the others, 
and in this way the large clusters of tubularians are rapidly formed. 
Several species of Campanularians are also to be found attached to 
the piles and timbers of wharves and bridges. At Wood’s Hole the 
most abundant species was Obelia pyriformis, which grew in great pro- 
fusion on the piles just below low-water mark. Itisa delicate and much 
branched species, with elongated, pear-shaped, reproductive capsules, 
and is beautifully phosphorescent. On the hull of an old wreck in 
Wood’s Hole passage, where the tide flows with great force, the Obelia 
flabellata was found in abundance, though it does not appear to have 
been noticed on this side of the Atlantic before. It has very elongated, 
slender, simple, but crooked stems, with numerous, alternate, short, 
forking, fan-shaped branches ; these generally fork close to their origin, 
the divisions diverging in opposite directions. The hydroid calicles 
(hydrothece) are small, cup-shaped, or broad bell-shaped, with a smooth 
rim, and they are borne on slender pedicles that are of various lengths, 
but mostly short and composed of only four to six rings. The repro- 
ductive capsules (gonothec) are urn-shaped, with a short, narrow neck ; 
they are borne on short pedicles, of few rings, arising from the axils of 
the branches. Some of the specimens were eight or ten inches long. 
