NORTH AMERICAN EARLY TERTIARY BRYOZOA. 395 



:i new genus to receive this species. The ovicelled specimens are very rare and 

 we were not able to prepare many sections. 



The last tubules of the distal zooecia form on the ovicell a circle of areolae; it 

 appears to be formed by a thickening of the olocyst. The two avicularia are very 

 constant ; they give to the zooecia a vague aspect of a 'bafs head. 



Affinities. The zooecia much resemble those of the genus Hippozeugosella; 

 they differ from it in the absence of a small, distal tongue; their mode of gemma- 

 tion is also different. 



This species differs from Hippodiplosia petiolus Lonsdale, 1845, and from 

 Hippodiplosia falcifcra in the very constant presence of two oral symmetrical 

 avicularia and in its very narrow zoarium. 



Occurrence. Middle Jacksonian: Wilmington, North Carolina (common); 

 near Lenuds Ferry, South Carolina (common) . 



Cotypes. Cat. No. 64095, U.S.N.M. 



HIPPODIPLOSIA PETIOLUS Lonsdale, 1845. 

 Plate 52, figs. 1-4. 



1845. Eschara petiolus LONSDALE, Account of twenty-six species of Polyparia obtained from 

 the Eocene Tertiary formation of North America, Quarterly Journal Geological 

 Society, London, vol. 1, p. 528, text figure. 



(ha, 0.15 mm. . [3=0.80-0.90 mm. 



Measurements. Aperture {-, A 1 A /.ooecia< 7 



U2=0.30-0.32 mm. 



AVe have had the good fortune to find some specimens of this species which no 

 observer has noted since 1845. There are no cardelles present. The ovicell is little 

 salient ; it is bordered by areolae and garnished with short radiating costules ; it is 

 open above the aperture, but lower than the poster; it may therefore be closed by 

 the operculum, for its exterior orifice is identical with the interior aperture and 

 with the neighboring apertures (fig. 4). The frontal is a tremocyst with tubules 

 supported by a very thin olocyst (fig. 3), with which it is closely joined. These 

 tubules are rather large; they are developed irregularly and give to the zooecia this 

 "increased convexity," noted by Lonsdale (fig. 2). There is sometimes a small 

 avicularium to the right or left of the aperture. The tremopores are easily filled 

 up in fossilization. 



Affinities. Its zoarium is formed of large bilamellar fronds like Hippodiplosia 

 falcifera, but the present species differs in the practical absence of avicularia and 

 in its smaller tremopores. 



The species differs from Ilippodiplosia vespertilio in the absence of avicularia 

 and in its large, expanded fronds. 



Occurrence. Middle Jacksonian: Eutaw Springs, South Carolina (rare). 



Plcsiotypes.C*t. No. 64094, U.S.N.M. 



HIPPODIPLOSIA FALCIFERA, new species. 

 Plate 52, figs. 13-16. 



Description. The zoarium is free, formed of two lamellae, back to back, and 

 inseparable; the fronds are wide, large, and flabellate. The young zooecia are 



