NORTH AMKKK'AN EARLY TERTIARY BRYOZOA. 401 



HIPPOZEUGOSELLA MARG1NATA. new species. 



Plate 53, figs. 9-11. 



Description. The zoarium is free, bilamollar; the two lamellae are separated 

 by some zooeciules; they are biserial. The zooecia are little elongated, distinct, 

 rhomboidal, separated by a salient thread; the frontal is convex and formed by a 

 tremocyst with large polygonal pores. The aperture is elliptical, oblique; the 

 peristome is thin, little salient, interrupted toward the back by a small, inconstant 

 tongue. The ovicell is hyperstomial, globular, salient, covered with tremopores like 

 the frontal. 



,, f Affl=0.15 mm. . I 3=0.85-0.95 mm. 



Measurements. Aperture), _,_ Zooeciau -. . 



[(.0=0.1.0 mm. u.s=0.4o-0.55 mm. 



Affinities. This new species differs from HipposeugoseUa arcuata in the 

 zooeciules which separate the lamellae (fig. 11) and in its zooecial length smaller and 

 less than 1 mm. 



It differs from Hipposengosella inflata in the absence of peristomial avicularia 

 and in the size of its tremopores. 



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



Cotypes.Ctit. No. 64100,U.S.N.M. 



HIPPOZEUGOSELLA INFLATA, new species. 



PInte 53, figs. 12-20. 



Description. The zoarium is free, bilamellar; each lamella is biserial. The 

 zooecia are elongated, distinct; the frontal is very convex and formed of a tremo- 

 cyst with very small pores. The aperture is somewhat elliptical or orbicular; 

 two very small cardelles separate the anter from the smaller poster; the peristome 

 is little salient and is interrupted by a small, distal tongue. Two large tubular 

 avicularia are placed symmetrically on each side of the aperture. 



(fla=0.12-1.14mm. . | 3=0.60-0.80 mm. 



Measurements. Aperture \ , . , /ooeciai, - .- 



Ua= 0.10mm. us=0.40mm. 



Variations. The young zooecia are provided with a small distal tongue (fig. 

 12) and the avicularia there are replaced by some tuberosities. The edge of the 

 zoarium sometimes presents some intercalated zooeciules (figs. 17, 19), although 

 sometimes they are wanting (fig. 18). Under the influence of calcification the 

 zooecia are flat or very convex (fig. 14) or very wide (fig. 16). 



Affinities. This species differs from Hipposeugosella marginata and Hippo- 

 seugosella arcuata in the spesence of the two avicularia. 



In its general aspect and its avicularia it has much resemblance to Hippo- 

 zeugosella sexordinata; but it differs in the disposition of its zoarium, which 

 possesses only four longitudinal rows of zooecia. 



Occurrence. Middle Jacksonian: One-half mile southeast of Georgia Kaolin 

 Co. Mine, Twiggs County, Georgia ; Baldock, Barnwell County, South Carolina. 



C'otypes.Cat. Nos. 64101, 64102, U.S.N.M. 

 55899 19 Bull. 106 26 



