NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
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Genus AECHMELLA Canu and Bassler, 1917. 
1917. Aechmella Canu and Basslee, Synopsis of American Early Tertiary Cheilostome 
Bryozoa, Bulletin 96, United States National Museum, p. 29. 
The polypidian convexity is little prominent. The opesiules are round, lateral 
indentations. The opesium is often contracted by two lateral teeth at the level of 
the opercular hinge. The ovicell is endozooecial. The avicularium is interzooecial, 
smaller than a zooecium, lozenge shaped, with the form of the head of a lance. 
Genotype. — Aechmella filimargo Canu and Bassler, 1917. 
Range.- — Cenomanian-Miocene. 
The genus Aechmella is in effect Gargantua with avicularia. It may also be 
regarded as Floridina with avicularia replacing the onychocellaria. 
The species of the genus are : 
Aechmella ( Cellepora ) michaudiana D’Orbigny, 1850. 
Aechmella { Cellepora ) hippocrepis Hagenow, 1851. 
Aechmella {G ellepora) roemeri Lonsdale. 
Aechmella {G ellepora) xiphia D’Orbigny, 1852. 
Aechmella (G ellepora) xanthe D’Orbigny, 1852. 
Aechmella ( Cellepora ) urania D’Orbigny, 1852. 
Aechmella {hi embranipora) depressa MacGillivray. 1901. 
Aechmella {hi embranipora) concinna MacGillivray, 1904. 
Aechmella {hi embranipora) ambigua MacGillivray, 1904. 
It is probable that one part of Homalostega Marsson, 1887. may be classed in 
this genus. 
AECHMELLA CRASSIMARGO, new species. 
Plate 37, figs. 1, 2. 
Description. — The zoarium incrusts shells. The zooecia are small, slightly 
elongated, joined by their mural rims; the mural rim is incomplete, projecting in 
front, thick on the borders , distinct from the cryptocyst. The cryptocyst is shallow, 
a little convex, and smooth; the opesium is almost transverse, trifoliate, contracted 
by two lateral teeth at the level of the opercular pivot; the polypidian convexity 
is scarcely visible; the opesiular indentations are shallow and symmetrical. The 
ovicell is endozooecial. The ancestrula is a small zooecium of the same form as the 
normal ones. The avicularium ir interzooecial, smaller than the zooecia, lozenge- 
shape, with a small distal canalicule and an elliptical opesium. 
„ \ho=0. 08-0.10 mm. 
Measurements.— Opesnun j Z( , =0 12 _0.14 mm. 
Zooecium 
(including the opesiular 
indentations) 
73=0.32-0.40 mm. 
lz= 0.24-0.30 mm. 
Affinities. — We have observed only a small number of specimens which were 
thought for a while to represent forms of ancestrular zooecia of Aechmella fili- 
margo. Nevertheless, we now believe it necessary to consider this a distinct 
