338 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
us more useful to preserve it. at least provisionally, for all the species imperfectly 
studied and classed. 
All the other species have the ovicell closed by the operculum and form a 
heterogeneous group. 
The function of the avicularia is unknown, but it has certainly not the univer- 
sality of the hydrostatic system. However, on many bryozoa, the avicularia 
appear to be indispensable, for they are constant in form and position. For 
example, the group of Schizoporella auriculata (genus Schizomavella ) is orna- 
mented by a very constant median avicularium. 
On other species the avicularia occupy a lateral or eccentric position. They 
belong to the still poorly defined groups of SchizoporeZZa vulgaris , including the 
fossil forms, Eschara phymatopora Reuss. 1869, and Lepralia schizostoma MacGril- 
livray, 1898, of SchizoporeZZa argentea with the fossil representative Schizoporella 
terebrata Maplestone, 1901, and of Schizoporella spinifera. 
A number of Schizoporellae are absolutely deprived of avicularia; they have 
been divided into the genera Phonicosia , Arthropoma , and Dakaria , according to 
the Special function of the rimnle. 
A rather important group appears to have a little chitinized operculum. The 
functions of this important organ are then assumed by the peristome specially devel- 
oped; this is the curious genus Metroperiella. The group of Waters with large 
operculum does not appear a natural one to us. 
Genus SCHIZOPODRELLA Canu and Bassler, 1917. 
1917. Schizopodrella Canu and Bassler, Synopsis of American Early Tertiary Cheilostome 
Bryozoa, Bulletin 96, United States National Museum, p. 40. 
The ovicell is hyperstomial. It opens above the aperture by a special opening 
closed by a special membrane and without connection with the operculum; it 
surmounts this aperture without inclosing it. The inferior border of the aperture 
is somewhat concave and bears a narrow rimule. The frontal is a tremocyst 
direct or covering a very thin olocvst finely perforated. The muscular attach- 
ments are generally at a distance from the border of the operculum. There are 
oral glands. 16-21 tentacles. 
Genotype. — Schizopodrella ( Lepralia ) unicornis Johnston, 1847. 
Range. — Lutetian-Recent. 
Waters in 1913 (p. 505) differentiated this genus without naming it. Schizo- 
podrella differs from Stephanosella in the tremopores which ornament its frontal 
and ovicell. It differs from Lacer-na in the absence of areolae. 
The recent species of this genus are : 
Schizopodrella ( Lepralia ) unicornis Johnston, 1847. 
Schizopodrella (Schizoporella) longirostris Hincks, 1888. 
Schizopodrella (Lepralia) errata Waters, 1879. 
Schizopodrella (Schizoporella) eZmwoodiae Waters, 1900. 
Schizopodrella (Schizoporella) nivea Busk, 1884. 
Schizopodrella (L^epralia) linearis Hassall, 1841. 
