NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
617 
ACANTHIONELLA SIMPLEX, new species. 
Plate 2, fig. 6. 
Description. — The zoarium is free, bilamellar, bifurcated. The zooecia are 
indistinctly oriented; the frontal is formed of a thick olocyst bearing a large 
suborbicular and salient avicularium. The peristome is very deep ; the peristomice 
is oval and bears on its proximal lip a sort of flat and very prominent lyrula. The 
ovicell is hardly visible exteriorly; it is hyperstomial and opens widely into the 
peristomie. 
Affinities. — The only specimen found has been figured. We have not been 
able to study this species in detail; but it was urgent to mention the occurrence 
of the genus in this stage. 
It differs from Acanthionella typica Gabb and Horn, 1862, in the presence 
of a single frontal avicularium (and not 3 or 1) and in its lyrula attached to the 
peristomice (and not to the apertura). 
It differs from Acanthionella occioporosa in the absence of frontal gibbosities 
and in the rarity of its frontal avicularia. 
Occurrence.— Lowest Eocene (Bryozoan bed at base of Aquia formation) : 
Upper Marlboro, Maryland (very rare). 
Holotype. — Cat. No. 63781, U.S.N.M. 
Genus KLEIDIONELLA Canu and Bassler, 1917. 
1917. Kleidionella Canu and Bassler, Synopsis of American Early Tertiary Cheilostome 
Bryozoa, Bulletin 96, United States National Museum, p. 72. 
The apertura is oval. The frontal is a very thick olocyst. The ovicell is 
hyperstomial and lodged in the olocyst of the distal zooecia ; it opens into the 
peristomie. There are some small and some large interzooecial avicularia. No 
lyrula. 
Genotype. — Kleidionella grandis Canu and Bassler, 1917. 
Range. — Claibornian — Vicksburgian. 
The abundance of cumulate zooecia and the absence of lyrula distinguishes 
this genus from the preceding one, Acanthionella. 
KLEIDIONELLA GRANDIS Canu and Bassler, 1917. 
Plate 7S, figs. 1-17 ; plate 79, fig. 1. 
1917. Kleidionella grandis Canu and Bassler, Synopsis of American Early Tertiary 
Cheilostome Bryozoa, Bulletin 96, United States National Museum, p. 72, pi. 6, 
figs 9, 10. 
Description. — The zoarium is very large , compressed, formed of bifurcated 
fronds almost in the same plane, attaining toward the base 2 cm. 5 mm. in width. 
The zooecia are disposed in two groups, back to back, and inseparable. The 
axial zooecia, bade to back, are oriented; all the other zooecia are cumulate. The 
superficial zooecia are distinct, urceolate, little raised, very oblique; the frontal 
is quite convex, smooth, bearing 0 to 3 improminent avicularia with pivot; the 
