NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
97 
reduced entirely to the lateral walls. Total regeneration manifests itself in a very 
thin mural rim within the opesium. 
The dimensions of the opesium are 0.50 mm. to 0.55 mm. by 0.40 mm. measure- 
ments which are very close to those of Membranipora laxa from Tunis as figured 
by Canu. The granulations Of the mural rim are much rarer than in the specimens 
from Tunis; they must be very irregular in occurrence, for Reuss did not mention 
them at all. If our American specimen be correctly determined, it appears here 
in a lower geologic horizon than in Europe. 
This species is very close to Membranipora filum Jullien, 1 but its dimen- 
sions are smaller and its zooecia are relatively more elongated in which it 
approaches the specimens cited by Calvet. It is evident that the great structural 
simplicity of such species makes their determination a matter of great care and 
of which one can not be exactly certain without the study of numerous specimens. 
Occurrence. — Claibornian (Gosport sand) : 1 mile southwest of Rockville, 
Clarke County, Alabama (very rare). 
Geological distribution. — Priabonian of Vicentin (Reuss, Waters) ; Chattiari 
( = Casselian) of Germany (Reuss) ; Eocene of Tunis (Canu). 
Plesiotype. — Cat. No. 63848, U.S.N.M. 
MEMBRANIPORINA CLAVIFORMIS, new species. 
Plate 19, fig. 14. 
Description. — The zoarium is free and club shaped , quite slender in the lower 
part, composed of zooecia disposed about an imaginary axis. The zooecia are large, 
elongate, somewhat indistinct because their mural rims are often confluent; the 
mural rim is thick, round, smooth. The opesium is median and elliptical. Between 
the superior opesia there are small triangular cavities without special walls. The 
larger zooecia measure 0.70 mm. by 0.24 mm. 
Affinities. — Only the single specimen figured has been discovered. It bears a 
resemblance to Farcimia , but we have been able to observe neither articulation nor 
endozooecial ovicells; moreover, there are six longitudinal series of zooecia. It is 
1 The bibliography of this recent species is as follows : 
1872. Biflustra lacroixi Smitt, Floridan Bryozoa, Kongl. Svenska Vetenskaps-Akademiens Handlingar. 
vol. 10, No. 11, p. 18, pi. 4, figs. 85-88. 
1902. Membranipora reticulum Calvet, Bryozoaires des cotes de Corse, Travaux de l’Institut de Zooiogie 
de University de Montpelier, ser. 2, Mem. 12, p. 14. 
1903. Membranipora, filum Jullien, Bryozoaries provenant des Campagnes de VHironclelle, p. 41, 
pi. 5, fig. 4. 
1914. Membranipora lacroixii Osburn, The Bryozoa of the Tortugas Islands, Florida, Publication 
Carnegie Institution of Washington, No. 182, p. 193. 
Smite’s figures, 85-87, indicate clearly the presence of triangular interopesial cavities with individual 
walls. Jullien thought this was an error, and that the species bore two spines placed on the distal triangu- 
lar parts of the zooecium. Canu does not believe that Smitt could have committed such an error in figuring 
the form. Osburn has collected from the Tortugas Islands a specimen which he states is similar to Smitt's 
figures, and which presents the usual characters of Conopeum lacroixii. But without doubt the species 
figured by Smitt is provided with a mural rim much narrower than Busk’s species, and for this reason it 
will perhaps be convenient to consider it a distinct species. The species of Jullien and Calvet is also very 
probably another. 
55899— 19— Bull. 106 7 
