NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



827 



Measuremen ts. 



Affinities. This species exteriorly resembles worn specimens of Ascosoecia 

 l'o>nit>t:ns; it differs from it in the great thickness of the walls of the mesopores. 



It differs from Trctoei/flocrin n'tii-ulatu in its branched, nonreticulate and 

 smaller zoarium, in its much less numerous mesopores, and in its apertures, which 

 are arranged in somewhat regular quincunx. 



Occurrence. Midwayan (Clayton limestone) : Mabelvale, near Little Rock, 

 Arkansas (rare). 



Cotypcs.Czt. No. 65256, U.S.N.M. 



TRETOCYCLOECIA GRANDIS, new species. 

 Plate 150, dgs. 7-10. 



Description. The zoarium is flat, cylindrical, branched. The tubes are, 

 cylindrical or polygonal, bent obliquely at their extremity. The peristome is thin, 

 orbicular, salient. The apertura is large. The mesopores are large, polygonal, 

 irregularly grouped, and always closed by a calcareous pellicle rather resistant and 

 finely perforated. The ovicell is orbicular. 



Diameter of the apertura 0.10 mm. 



Diameter of the peristome 0.15 mm. 



Diameter of the branches 3.20 mm. 



Diameter of the mesopores . 0.10 mm. 



Diameter of the ovicell 1.25 mm. 



Affinities. This species offers much the aspect of the Pustulopora (Clausa) 

 retifcra Stoliczka, 1861, of the Latdorfian, the type of which we have not been 

 able to compare. It differs in its mesopores, the diameter of which never surpasses 

 that of the tubes,' and in larger apertures (0.10 and not 0.06 mm.). 



The figured specimen is the only one found. The study of the species is 

 therefore incomplete. 



Occurrence. Lower Jacksonian (Moodys marl) : Jackson, Mississippi (very 

 rare). 



Holotype.Crt,. No. 65372, U.S.N.M. 



TRETOCYCLOECIA RETICULATA, new species. 



Plate 149, figs. 1-14. 



Description. The zoarium is free, solid, cylindrical, large, reticulate. The 

 tubes are very long, cylindrical, bent at a right angle at their extremity; the 

 apertures are orbicular, grouped in irregular zones (in section). The mesopores 

 are exteriorly small, polygonal, with thin walls, grouped in irregular, transversal 

 zones, and of a large diameter in section; the walls are vesicular. Diaphragms 

 in the tubes are rare. The ovicell is orbicular, hardly salient. 



Diameter of the apertura 0.12 mm. 



Measurement.?. Diameter of the mesopores 0.05 mm. 



Diameter of the branches__ _ 5.00 mm. 



