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 stems 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 (mo.) 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 (fwnic) 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. 



Kecognizable 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 

 hryozoa. The ovary (ov.) occurs about the middle part of the body 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. 



