436 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Occurrence. — Vicksburgian (Marianna limestone) : Salt Mountain, 5 miles 
south of Jackson, Alabama (very rare) ; near Claiborne, Monroe County, Alabama 
(rare) ; deep well in Escambia County, Alabama (very rare). 
Cotypes. — Cat. No. 64293, U.S.N.M. 
ENOPLOSTOMELLA RHOMBOIDALIS, new species. 
Plate 90, figs. 10-16. 
Description. — The zoarium is free, cylindrical, or somewhat compressed, bi- 
furcated, formed of two lamellae, back to back, and inseparable. The zooecia are 
little distinct, elongated, rhomb oi-clal , separated by a prominent thread; the frontal 
is somewhat convex and formed by a thick tremocyst with very large tubules resting 
on a thin olocyst irregularly perforated. The apertura is very oblique, semilunar, 
with a proximally concave border; the peristomice is elongated, much buried, with 
a triangular rimule-spiramen. The ovicell is hyperstomial, opening into the per- 
istomie, little salient, globular, ornamented with large tremopores. In the peris- 
tomie there is a small triangular avicularium with pivot, placed transversely. 
Measurements. — Peristomice (kpe— 0.16 mm „ . \Lz=0. 65-0.75 mm. 
(exterior) |7pg=0.12 mm. °° eCla 17s=0.45-0.60 mm. 
Variations. — The thread separating the zooecia is quite variable and changes 
the external aspect considerably; it is thickened laterally (fig. 12) or only near 
the apertura (fig. 14). It gives to the zooecia a greater width (fig. 13) or less 
(fig- 15). 
In the interior, the structure is more regular, but it may be noted that the 
small perforations of the olocyst are not regularly arranged in quincunx, an occur- 
rence which is very rare. 
Affinities. — This species differs from Enoplostomella crassimuralis , in which 
the zoarium has some resemblance, in its rhomboidal form, its solid and not hollow 
zoarium and its peristomice still more imbedded. 
It differs from Enoplostomella defixa , also with a cylindrical zoarium, in its 
smaller and more hidden peristomial avicularium, its much less salient ovicell and 
in its less zooecial width. 
O commence. — Vicksburgian (Marianna limestone) : One mile north of Mon- 
roeville, Alabama (rare) ; 2-J miles north of Millrv, Washington County, Alabama 
( rare) . 
Cotypes . — Cat. No. 64291, U.S.N.M. 
ENOPLOSTOMELLA DEFIXA Canu and Bassler, 1917. 
Plate 91, figs. 12-21. 
1917. Enoplostomella defixa Canu and Basslek, Synopsis of American Early Tertiary 
Cheilostome Bryozoa, Bulletin 96, United States National Museum, p. 46, pi. 4, fig. 8. 
Description . — The zoarium is free, cylindrical, vinculariform, formed of six 
to seven longitudinal rows of zooecia. The zooecia are indistinct; the frontal is 
little thickened, convex, formed of a tremocyst with large pores placed above an 
