NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
675 
Genotype. — Spiropora elegans Lamouroux, 1821. 
The ovicell of Spiropora has never been found, in spite of the large number of 
specimens collected. It is probable that it does not exist and that the larva is 
developed in a small distal sack of an ordinary tube. An important character is 
the presence of diaphragms in the tubes at different heights. 
SPIROPORA MAJU5CULA, new species. 
Plate 128, figs. S-13. 
Description. — The zoarium is formed of very large , cylindrical and dichoto- 
mous branches. The tubes are distinct, flat, separated by a salient thread. The 
fascicles form annular, salient, regular verticells, broken and incomplete at the 
bifurcations. 
Measurements . — 
Diameter of the peristome, 
Diameter of the tubes 
Distance between the verticells 
Diameter of the branches 
0.33 mm. 
0.25 mm. 
1.08 mm. 
1.50-2.00 mm. 
Affinities.— This is the largest species of Spiropora known. Its regularity is 
rather remarkable. In longitudinal section the diaphragms appear not only at the 
base of the tubes, but at different heights ; they are scattered or close together. In 
transversal section the zooecia are separated by a clear line, the calcification of 
the tubes being more intense in the interior. 
Occurrence. — Middle Jacksonian: Near Lenuds Ferry, South Carolina (very 
common); Eutaw Springs, South Carolina (common). 
Cotypes. — Cat. No. 65322, U.S.N.M. 
(b) TREPOSTOMATOUS LIKE CYCLOSTOMATA. 
Family HETEROPORIDAE Pergens and Meunier, 1886. 
1886. Pergens ancl Mexjnier, La faune des Bryozoaires garumniens de Faxe, Annales de la 
Soci6te Royale malacologique de P.elgiqne, vol. 21, p. 223. 
No ovicell. The tubes are cylindrical. 
Historical. — We here reunite in the same family the species grouped formerly 
under the two well-known families — Heteroporidae and Cerioporidae. We now 
know that the presence of mesopores is not a family character. The family Ceri- 
oporidae not having been created until 1891 b}^ Hennig, priority is secured by the 
family of Pergens and Meunier. 
Organization.- — All the known anatomical features have been summarized in 
figure 219 ; they are of little importance. They show T us, however, that the parietal 
vesicles do not contain any special organ and do not constitute a character of classi- 
fication of great value. We know (see General Consideration, on page 634) that 
the tubes are not exactly adjacent; they are separated (according to Calvet) by the 
