NORTH AMERICAN EARLY TERTIARY BKYOZOA. 



519 



in the genotype. However we have not yet concluded that they are absent, as in 

 such small zoaria they are fragile. One of the sections taken through the zoarial 

 apophyses shows that these are hollow ; we are absolutely ignorant of their use, for 

 we have no analogous case in the recent species. 



Affinities. This species is easy to differentiate from SemihasvieUia tnpora; 

 its small peristomial pores are much smaller and hardly visible; its zooecial length 

 is larger (more than 0.40 mm.) ; the zoarial apophyses are smaller. 



Occurrence. Jacksonian (Zeuglodon zone) : Cocoa post office, Choctaw County, 

 Alabama (very rare). 



Upper Jacksonian (Ocala limestone) : Chipola River, east of Marianna. 

 Florida (rare) ; Old Factory, about 1-J miles above Bainbridge, Georgia (rare). 



Vicksburgian (Marianna limestone) : West bank of Conecuh River, Escambia 

 County, Alabama (very common) ; 

 2^ miles north of Millry, Washington 

 County, Alabama. 



Cotypes.C-Ai. No. G4166, U.S.N.M. 



SEMIHASWELLIA (?) CLARA, new species. 



Plate 66, figs. 28, 29. 



Description. The zoarium is free, 

 a little compressed, formed of three 

 rows of zooecia disposed on only one 

 side ; the dorsal is granular and bears 

 two lateral rows of alternate salient 

 avicularia with pivot. The zooecia 

 are distinct, oval, a little elongated; 

 the frontal is convex and ornamented 

 with some tremopores irregularly disseminated. The peristome is salient, thin, 

 bearing one or two very small avicularia ; the peristomice is orbicular. The spira- 

 men is placed on the median axis of the zooecium in the vicinity of the peristomice. 



lhpe=O.Q5 mm. 



FIG. 152. Genus Gigantopora Ridley, 1881. 

 A-E. Gigantopora lyncoides Ridley, 1881. A. B. 

 Zooecia, seen from the front and in profile. (After 

 Ridley, 1881.) C. Young zooecium. D. Normal zooe- 

 cium. E. Operculum. (C-E after Kirkpatrick, 1888.) 



Measurements. Peristomice 



, ... 



llpeO.Qo mm. 



Zooecia 



Affinities. We have only found the two specimens figured. They form a rather 

 divergent type in this genus in the distinct form of the zooecia and in the nature 

 of the walls. Some further study is necessary to properly classify this species. 



Occurrence. Middle Jacksonian: Near Lenuds Ferry, South Carolina (rare). 



Cotypes.Cat. No. 64168, U.S.N.M. 



Genus GIGANTOPORA Ridley, 1881. 



1881. Gigantopora RIDLEY, Zoological collections made during survey of H. M. S. Alert. 

 Proceedings Zoological Society London, p. 47. 



The apertura bears a rimule. The frontal is an olocyst. The spiramen is 

 inconstant ; it is almost as large as the apertura. 



