400 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



a double rounded indentation. The ovicell is globular, salient, ornamented with 

 small pores, as the frontal ; its orifice is very large and placed above the aperture. 

 In the peristomie itself there is a small avicularium. 



(A,a=0.13mm. . fZ. 



Measurements. Apertures, - ... Zooecia ' 



Ua=0.09mm. lfe 



Variations. The labial processes which form the peristomie give to the species 

 a deformed and curious aspect; they are very fragile and break very easily in fos- 

 silization. The broken portion shows the small peristomial avicularium. 



The mode of gemmation is interesting. It occurs on the edge; the visible 

 zooeciules form the base of the distal zooecia of the other face. 



Affinities. This species differs from Hippozeugosclla (Cucuttipora) tetrasti- 

 ch-a MacGillivray, 1895, in its smaller dimensions and its avicularium much smaller 

 and never frontal. 



It differs from Hippozeugosetta arcuata in the absence of the peristomial tongue 

 and in the larger development of its labial processes. 



The only specimen found in here figured. 



Occurrence. Middle Jacksonian: Eighteen miles west of Wrightsville, John- 

 son Coimty, Georgia (very rare). 



Holotype.Cat. No. 64098, U.SN.M. 



HIPPOZEUGOSELLA ARCUATA, new species. 



Plate 53, figs 21-25. 



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

 zooecia are distinct, elongated, arched; the frontal is very convex; it is formed of 

 a direct tremocyst with rather large pores. The aperture is oblique, elliptical or 

 orbicular, imbedded. The peristome is somewhat salient, and its distal part is a 

 little isolated tongue. The ovicell is hyperstomial, globular, salient, covered with 

 tremopores like the frontal ; it is opened by a large orifice above the aperture. No 

 avicularia. 



. |a=0.13-0.14mm. . [3=1.10-1.20 mm. 



Measurements. Aperture 7 Zooecia{7 n on mm 



Ua=0.11-0.12 mm. =U.dU mm. 



Affinities. This species is very well characterized by its much arched zooecia. 

 Certain fragments are narrowed toward the bottom as if the zoarium might have 

 been articulated. We have also found a triserial fragment (fig. 25) growing from a 

 single zooecium. The zooecia and the little tongue are quite visible on the edge of 

 the zoarium (fig. 21, 23) ; between the zooecia there are no zooeciules as in the 

 other species of the same genus. 



This species differs from Hippozeugosella distorta in its much less developed 

 labial processes and in its arched and much longer zooecia (Zs=1.10 instead of 

 0.75 mm.). 



It differs from Hippozeugosella marginata in its nonmarginated zooecia, its 

 smaller tremopores, and its zooecial length greater than 1 mm. 



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

 mon). 



Cotypes.Ca*,. No. 64103, U.S.N.M. 



