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 ic 

 the presence of diaphragms in the tubes at different heights. 



SPIROPORA MAJU3CULA, new species. 



Plate 128, figs. 8-13. - ' ^ 



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. 



f Diameter of the peristome 0.33 mm. 



Measurements.- ]**** of the tubes 0.25 mm. 



Distance between the verticells 1.08 mm. 



[ Diameter of the branches 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. PERGEXS and METTNIER, La faune des Hryozoaires garuuiniens de Faxe, Annales de la 

 Socite Royale malacologique de Belgique, vol. 21, p. 223. 



Xo 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 1894- by 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 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 



