NORTH AMERICAN EARLY TERTIARY BRYOZOA. 783 



Some branches (figs. 14, 15) are beyond all description on account of their great 

 irregularity. The fascicles are quite salient (figs. 7, 8, 14). but they are fragile 

 and break easily (fig. 16). 



The fascicles are quite distant from the median crest ; also on the longitudinal 

 sections there are no zooecia with the apertura visible (fig. 22). In order to see the 

 apertura of the zooecia it is necessary to make a meridian section by the prolonged 

 abrasion of the frontal (fig. 23). 



The miscroscopic structure of the zooecial walls (fig. 24) is rather difficult to 

 comprehend. 



Affinities. This species is quite odd and easy to determine; it is impossible 1 1 

 confuse it with the others. One can not determine the isolated branches, for the 

 reader can believe in the existence of many species of which intermediate stages 

 appear in large numbers of specimens. 



The comparison with the French species has been made specimen with speci- 

 men and the identification is absolutely certain. 



Occurrence. Vicksburgian (Marianna limestone) : Salt Mountain, 5 miles 

 south of Jackson, Alabama (common) ; near Claiborne, Monroe County, Alabama 

 (common) ; Murder Creek, east of Castlebury. Conecuh County, Alabama (very 

 common) ; west bank Conecuh River, Escambia County, Alabama (very com- 

 mon) ; Escambia County, Alabama (deep well) (rare). 



Vicksburgian (Byram marl) : One-fourth mile west of Woodwards, Wayne 

 County,- Mississippi (common). 



Geological distribution. Auversian of Biarritz (Canu). 



Plesiotypes.C&t. Nos. 65441-65445, U.S.N.M. 



IDMONEA GRANDIORA. new -species. 

 Plate 162, figs. 1-3. 



Description. The zoarium is free, linear, fixed by an expanded base, com- 

 pressed. The fascicles are somewhat salient, close together, arranged alternately 

 on each side of the median line and formed of three equal zooecia. The tubes 

 are invisible ; the peristome is thin ; the apertura is large. 



Diameter of the zooecia 0.20 mm. 



Distance between the fascicle? 0.20-0.22 mm. 



Width of the fascicles 0.16-0.18 mm. 



Width of the zoarium 0.60 mm. 



Affinities. Only the three specimens figured have been found. They ai-e of 

 interest merely on account of their great apertura and because this species exists in 

 the strata of Vicentin where Canu has recently discovered it. 



Occurrence. Vicksburgian (Marianna limestone) : One mile north of Monroe- 

 ville, Alabama (rare). 



Geological distribution. Priabonian of the Vicentin. 

 Holotype.C&i. No. 65472, U.S.N.M. 



Measurements. 



