NORTH AMERICAN EARLY TERTIARY BRYOZOA. 813 



even the recent ones, presents therefore much difficulty. As the oeciostomes and 

 the cancelli can only give constant characters, we have given a summary in figure 

 256 of our knowledge of these important organs. On the fossils we have not yet 

 discovered the complete oeciostome and this absence of character much weakens 

 the determinations. 



The first two zooecia issued from the ancestrula determines the direction of 

 the tubes in a given section. We call them directrices and they are always of a 

 smaller diameter than the other tubes. 



LICHENOPORA BOLETIFORMIS Eeuss, 1869. 



Plate 130, figs. 1-11. 



1869. L'a'iiopora boletiformis REUSS, Paliiontologische Studien liber die iilteren Tertiiir- 

 scliichten der Alpen, Denkschriften der k. Akaderuie der Wissenschaften, Wien, 

 vol. 29, p. 81, pi. 28, fig. 7 (1) (not Tecticavea boletiformis D'Orbigny, 1S54, nor 

 Lichenopora boletiformis Waters, 1884.) 



Description. The zoarinm is free and reposes on the substratum only by a 

 thin peduncle. It is formed of many lamellae superposed. Each lamella contains 

 many confluent subcolonies. The basal lamella is thick and striated concentrically. 

 The subcolonies are orbicular or elliptical with a large central area. The fascicles 

 are little salient, short, biserial or triserial. The tubes are small and deprived of 

 visor. The cancelli are larger than the tubes; they are polygonal and their walls 

 are thin. 



Diameter of the tubes _ 0.16 mm. 



Measurements. 



Diameter of the cancelli _ 0.20 



mm. 



Greatest dimension of the zoaria 1 cm. 



Variations. The fascicles become much attenuated and the zoaria have then 

 much resemblance to Ceriopora (fig. 6). The zoarium has no fixed form, but 

 a very convex ensemble is the most frequent. Each subcolony has no special basal 

 lamella. The tubes are polygonal (figs. 7, 8) in the sections but they are round 

 in the broken portion. The spinules of the cancelli (fig. 8) are small, numerous, 

 and arranged in longitudinal series. 



The median sections vary according to place where they are made. In a 

 section (fig. 10) perpendicular to the fascicles the tubes are seen from the front. 

 In section (fig. 11) practically within a fascicle the tubes appear in their length 

 and parallel to each other. 



Affinities. On account of its multiserial fascicles this species is very close to 

 Lichenopora mediterranea Michelin, 1848, and to Lichenopora vemtcosa Philippi, 

 1843. It is distinguished from them by the greater micrometric and zoarial dimen- 

 sions. 



Occi/.t'/'cnci'. Middle Jacksonian: Wilmington, North Carolina (common); 

 Eutaw Springs, South Carolina (very common) ; Baldock. Barnwell County, South 

 Carolina (rare). 



Geological distribution. Priabonian of the Vicentin (Reuss). 



Plesiotypes.C'&t. No. 65453, U.S.N.M. 



