826 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Family TRETOC Y CLOECIIDAE Canu, 1919. 
1919. Tetrocycloeciidae (in error for Tretocycloeciidae) Canu, Etudes sur les Ovicelles des 
Bryozoaires Cyclostomes (2), Bulletin Soeiete Geologique de France, ser. 4, 
vol. 17, p. 346. 
The ovicell is orbicular, flat, not salient, smooth, regular, and limited, traversed 
by tubes and sometimes by meso pores ad j acent to the latter. 
This family has a resemblance to the Diaperoeciidae, but differs from it in the 
flat orbicular and not globular form of the ovicell, and in the presence of the 
mesopores. 
Genus TRETOC YCLOECIA Canu, 1919. 
1919. Tetrocycloecia (in error for Tretocycloecia) Canu, Etudes sur les Ovicelles des 
Bryozoaires Cyclostomes (2), Bulletin Soeiete Geologique de France, ser. 4, 
vol. 17, p. 346. 
The tubes are cylindrical. The mesopores are irregularly directed ; their walls 
are vesicular. The tubes which perforate the ovicell are accompanied by the 
adjacent mesopores. 
Genotype.- — Tretocycloecia ( Heteropora ) clichotoma Reuss, 1817 (not Hage- 
now, 1851). 
Range. — Midwayan-Tortonian. 
TRETOCYCLOECIA (?) ATTENUATA Ulrich, 1882. 
Plate 109, figs. 1-9. 
1882. Heteropora attenuata Ulrich, American Paleozoic Bryozoa, Journal Cincinnati So- 
ciety Natural History, vol. 5, p. 144, pi. 6, fig. 12. 
1909. Sparsicavea attenuata Gregory, Catalogue Fossil Bryozoa in Department Geology 
British Museum, Cretaceous, vol. 2, p. 302. 
Description .— The zoarium is solid, cylindrical, branched, with branches 
rounded at the summit. The tubes are cylindrical, curved at their extremity (in 
section). The peristome is smooth, orbicular, not salient, imperfectly visible. The 
mesopores are rare, rounded, smaller than the tubes, with very thick walls and 
in section very short and with vesicular walls. 
Diameter of the aperture 0.08-0.10 mm. 
Diameter of the peristomes 0.10-0.16 mm. 
Measurements. Diameter of the branches 2.00 mm. 
Diameter of the mesopores 0.06-0.08 mm. 
Diameter of the ovicell 1.00 mm. 
Variations . — The number of the mesopores surrounding an aperture is rather 
variable. More often there is only one mesopore between the peristomes; some- 
times the mesopores are in groups of six or seven. The branches are sometimes 
dichotomous and sometimes arborescent. The distance between two mesopores is 
almost always greater than their diameter. 
The only ovicell discovered was broken; we are therefore not exactly certain 
of our generic determination. 
