220 
BULLETIN' 106, UNITED STATES NATIONAL MUSEUM. 
The opesiular indentations serve as a passageway for both the parietal and 
opercular muscles. Exteriorly the polypidian convexity quite resembles the poly- 
pide tube of Steganoporella ; but in the interior it is incomplete (pi. 35. fig. 16), 
and it is rare even that the tuberosities (t) bound it laterally. 
Irregularity is the rule in this genus; all the characters of the opesium are 
extraordinarily variable. Determination of the species is often difficult and causes 
much perplexity for the naturalist. 
The opesial processes often join the polypidian convexity, the opesiules thus 
becoming complete; in the interior the aspect is identical with that of Thalamo- 
porella. 
The known species of this genus are : 
Floridina ( Semieschara ) canui Brvdone, 1900. 
Floridina ( Gellepora ) crustulenta Goldfuss, 1828. 
Floridina {Semieschara) bimarginata D’Orbigny, 1852. 
Floridina (Mollia) ■ anti qua Smitt, 1873. 
Floridina vendoma Canu,- 1900. 
There has as yet been no evidence of the genus, in the American Cretaceous. 
If this observation be confirmed we will be obliged to repeat that the beginning 
of the Eocene is the time when the change in direction of the Atlantic currents 
occurred. 
FLORIDINA GRANULOSA, new species. 
Plate 35, figs. 1-4. 
Description. — The zoarium is bilamellar with distorted fronds. The zooecia 
are distinct, hexagonal, separated by a deep furrow. The mural rim and crvpto- 
cyst are covered with granulations more or less large. The opesium is large, a 
little elongated, trifoliate; the opesiular portion is large, orbicular and separated 
from the opercular portion by two salient teeth. The ovicell is endozooecial ; 
this is a distal convexity little apparent. The onychocellarium is elongated, 
elliptical, as large as the zooecium ; the opesium is oval, the point above and bears 
laterally two salient denticles. 
Measurements. — Opesium IAd= 0.22 mm. . |ZA=0.45-0.50 mm. 
of zooecia l lo— 0.15 mm. moecia o.35_o.40 mm. 
Opesium I7um=0.25 mm. • \Lon— 0.45-0.50 mm. 
of onychocellaria l lon= 0.15 mm. n ^ c loce ai mm \lon=Q. 35-0.40 mm. 
V aviations and affinities. — The ovicelled zooecia have an opesium and larger 
micrometric dimensions (fig. 1). We have observed some calcified zooecia (fig. 2) 
bearing a large central perforation. 
This species is very well characterized by the absence (not constant) of the 
polypidian convexity and by its frontal granulations. 
Occw'rence. — Lower Jacksonian (Moodys marl) : Jackson, Mississippi (rare). 
Cotypes. — Cat. No. 63980, U.S.N.M. 
