42 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
attached to rocks or other objects. Upon examination (fig. 1) the fluffy mass is seen 
to be made up of narrow branching steins with root-like filaments at the base. 
Under a lens each stem is noted to be made up of box-shaped, chitinous struc- 
tures — the zooecia, arranged in four longitudinal rows. The zooecia have a wide 
crescentic aperture near the distal end {wo.) on either side of which is a short, 
blunt spine. In front of some zooecia is a round structure — the ooecium (ooec ) , and 
on most of them is the bird’s-head appendage — the avicularium ( avic ), supported on 
a short stalk. Beneath the wall of the zooecia, which is simply the hardened and 
thickened cuticle of the animal proper, is the soft body wall. This body wall is gen- 
erally known as the endocyst , and some authors apply the term ectocyst to the 
hardened cuticle or zoarial skeleton. In this work, however, the term ectocyst desig- 
nates the outer membrane covering the zoarial skeleton. 
The anterior part of the polypide can be turned inside out like the fingers of 
a glove, within the posterior part. When this portion, the introvert , is extruded 
a circle of usually fourteen long slender tentacles {tent.) on a circular ridge or 
lophophore surrounding the mouth is seen at its anterior end. A pair of retractor 
muscles serves to retract the tentacles. Numerous cilia on the tentacles drive cur- 
rents of water with their contained food particles toward the mouth {mo). The 
tentacles are probably tactile and also may serve in respiration. The tentacle sheath 
is the enclosing wall of the introvert. 
The coelome or body cavity occupies a considerable part of the zooecial interior. 
A large double strand of spindle-shaped cells known as the funiculus {funic) con- 
nects the aboral end of the alimentary canal with the aboral wall of the zooecium. 
The body cavity contains a number of colorless corpuscles or leucocytes. 
Alimentary canal . — The mouth {mo) at the base of the tentacles opens into the 
pharynx (ph) which by a shorter constricted tube leads to the stomach. The 
coecum is a long conical projection of the stomach directed toward the aboral 
end of the zooecium, to which it is attached by the funiculus. The intestine is 
directed upward and nearly parallels the esophagus; it opens outside the lopho- 
phore not far from the mouth in the anal aperture {an). 
Nervous and excretory systems . — A small round ganglion located between the 
mouth and the anal aperture, giving off nerves to the various parts of the zooid, 
constitutes the nervous system. No special sense organs are developed. 
Recognizable excretory organs are absent. It is probable that the leucocytes 
carry on the collection of the nitrogenous waste matter. 
Reproductive organs . — Both sexes are united in the same zooid as in most 
brvozoa. The ovary {ov.) occurs about the middle part of the bod} 7 cavity and 
the testis in the lower portion. The latter gives rise to a spherical mass of cells, 
the spermatidia {sp.) which develop into sperms with long mobile tails. After 
the sperms become free from each other they move about in the body cavity where 
fertilization takes place. Only one mature ovum at a time is developed from the 
ovary. After fertilization the ovum passes into the ovicell or ooecium (ooec) where' 
development takes place. 
