142 
BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 
Genus EURYSTOMELLA Levinsen, 1909. 
1909. Eurystomella Levinsen, Morphological and systematic studies on the cheilostomatous 
Bryozoa, p. 314. 
Characters same as for the family. The operculum closes the ovicell. 
EURYSTOMELLA BILABIATA Hincks, 1884. 
Plate 37, fig. 6. 
1884. Lepralia bilabiata Hincks, Polyzoa Queen Charlotte Islands, Annals and Magazine Natural 
History, ser. 5, vol. 13, p. 49, pi. 3, fig. 1. 
1908. Lepralia bilabiata Robertson, The incrusting Cheilostomatous Bryozoa of the West coast of 
North America, University of California Publications, Zoology, vol. 4, no. 5, p. 298, pi. 21, 
figs. 61-64. 
Our fossil specimens of this species are mediocre and do not permit us to add 
any useful contribution to the knowledge of this remarkable species. We therefore 
have no modifications to add to Levinsen’s description. 
Occurrence. —Pleistocene: Dead Man’s Island, off San Pedro, California (rare). 
Habitat.— Pacific: California and Queen Charlotte Islands. 
Plesiotype. —Cat. No. 68635, U.S.N.M. 
Family STOMACHETOSELLIDAE Canu and Bassler, 1917. 
Genus LEIOSELLA Canu and Bassler, 1917. 
(For description see Bulletin 106, U. S. National Museum, p. 448.) 
LEIOSELLA EDAX, new species. 
Plate 22, figs. 1-6. 
Description. —The zoarium is free, unilamellar, often tubular; it was attached 
to the delicate radicells of algae. The zooecia are indistinct. The peristomice is 
very large, elongate, provided with a large rimule spiramen; the peristomie is 
deep; the apertura (in the interior) is semilunar with a concave proximal border. 
The ovicell is placed in the peristomie; it is widely open above the operculum; it 
bears a circular, very fragile frontal area. Around the peristomice there are three 
or four small, round, salient avicularia, with two denticles for pivot; they are 
sometimes transformed into large avicularia with spatulate mandibles. Another 
avicularium opens into the peristomie. 
,, , . \ha=0.\b mm. Zooecia \Lz = 0.40 mm. 
Measurements. Aperturaj^ _ Q 1M mm <mterior){k -0.30-0.35 mm. 
Affinities.—' The aspect of .this species is quite variable and depends solely on 
the number and development of the frontal avicularia. It appears very greedy for 
oxygen, a fact which is supported by the great thickness of its frontal wall and the 
activity of the calcareous secretion. Sometimes two small avicularia are replaced 
by a much larger one with large spatulate mandible. 
The peristomie is the real seat of life of this species. An avicularum (visible 
from the interior) opens into the lateral portion. The distal portion is reserved for 
the ovicell. Finally, the pseudo-rimule spiramen in the proximal portion is the 
orifice of the hydrostatic system. It is probable that the female polypide disap¬ 
pears by histolysis at the moment of the development of the embryos and the 
escape of the larva. 
Occurrence. —Lower Miocene (Chipola marl): Chipola River, Calhoun County, 
Florida (rare). 
Cotypes. —Cat. No. 68636, U.S.N.M. 
