NORTH AMERICAN EARLY TERTIARY BRYOZOA. 391 



HIPPOMENELLA TliBEROSA, new species. 

 Plate 51, Ggs. 4, 5. 



Description. The zoariuni incrusts bryozoa. The zooecia are large, elongated, 

 elliptical, or hexagonal, separated by a deep furrow; the frontal is very convex, 

 surrounded by a double row of areolae and decorated with tuberosities grouped in 

 lines radiating from the mucro. The aperture is semielliptical in the interior 

 with two cardelles placed very low ; on the exterior it is surrounded distally by a 

 peristome garnished with six large spines and proximally by a salient mucro. 

 The ovicell is large, elongated, salient, hyperstomial. little imbedded in the distal 

 zooecia, never closed by the operciilum; the two areas are garnished laterally with 

 an arched slit. The two avicularia are of equal dimensions; they are small, little 

 snlient, triangular, provided with a pivot, placed at some distance below the aper- 

 ture ; their beak is pointed downward and toward a neighboring aperture. 



,, I fia 0.14-0.16 mm. . f 7,3=0.84 mm. 



Measurements Aperture 7 A 1 Zooecia , . - 



Uo=0.14mm. [fe= 



Affinities. This is a splendid species. The frontal tuberosities are of pleuro- 

 cystal origin and the olocyst is easily visible below. 



The species differs from Hippomenella Ugulata. which shows some radial 

 granulations, in its larger micrometric dimensions (.3=0.84 and not 0.70 mm.) 

 and in its much less salient avicularia. 



Occurrence. Middle Jacksonian (Castle Hayne limestone) : Wilmington, 

 North Carolina (very rare). 



Holoti/pe.C&i. No. 64087, U.S.N.M. 



HIPPOMENELLA AXICULATA. new species. 



Plate 51, figs. 10-13. 



Description. The zoarium incrusts bryozoa. The zooecia are distinct, wide, 

 irregular in position ; the frontal is little convex, smooth, surrounded by three lines 

 of small and triangular areolae. The aperture is semielliptical with two cardelles, 

 placed quite low; the peristome supports six to eight distal spines; an enormous, 

 salient mucro, oblique or erect, lobate. hides the aperture more or less. The ovicell 

 is large, salient, imbedded in the distal zooecium, is hyperstomial and is never closed 

 by the operciilum; it frontal area is perforated with an arched slit. The avicularia 

 placed near the aperture are small and irregular. 



ffia=0.16mm. . ( Zs= 0.68-0.70 mm. 



Measurements. Aperture , n ., Zooecia { , 



[?a=0.14mm. \ 70=0.50 mm. 



Variations. The mucro forms in front of the aperture a small pallet, quite 

 variable in form and dimensions. We are ignorant of the physiologic use of this 

 organ, but it appears essential and analogous to that of the spines. If it be true 

 that their existence is for the purpose of capturing the diatoms, our species must 

 have been excessively voracious. What is strange is the absolute irregularity of the 

 mucro ; no one of them has any resemblance to the other and they are of all dimen- 

 sions. 



