392 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Affinities. The zooecia with a small mucro resemble Hippomenella ligulata, 

 but the present species differs in its wider zooecia (lz=0.50 and not 0,44 mm.), in the 

 presence of three rows of areolae and in the occurrence of a single avicularium. 



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

 Springs, South Carolina (rare). 



Cotypes.dd. No. 64090, U.S.N.M. 



HIPPOMENELLA CKASSICOLLIS. new species. 



Plate 51, figs. 14-19. 



Description. The zoarium incrusts bryozoa or shells. The zooecia are little 

 distinct, elongated ; the frontal is convex, surrounded with a double row of areolae, 

 covered by a very thick and finely granulated pleurocyst. The aperture is semi- 

 elliptical in the interior, with two cardelles placed very low; on the exterior it is 

 surrounded with a peristome, salient, very thick, supporting two to six large distal 

 spines. The ovicell is globular, salient, hyperstomial, embedded in the distal zooecia 

 and ornamented with large radial costules. On the frontal there are two or three 

 small triangular avicularia with pivots. 



[Aa=0.18mm. . fZs=0.60mm. 



Measurements.- Aperture , -..,. Zooecia < 7 - , 



lZffl=0.12mm. lfe=0. 50mm. 



Variations. The variable aspect of this species depends on the active intensity 

 of the pleurocystal calcification, which may be found shown in figures 16-19. The 

 small avicularia are irregularly placed (fig. 19) ; nevertheless they may be sym- 

 metrical (fig. 16) ; they are elongated in proportion to the deposition of the pleu- 

 rocyst with the result that they are always salient. The large costules of the 

 ovicell are placed above the two lateral areas, sometimes perforated. 



Occurrence. Upper Jacksonian (Ocala limestone) : Alachua, Florida (rare). 



Vicksburgian (Byram marl) : One-fourth mile west of Woodward, Wayne 

 County, Mississippi (very rare). 



Vicksburgian (Marianna limestone) : Near Claiborne, Monroe County, Alabama 

 (rare). 



Cotypes.C&t. Nos. 64091-64093, U.S.N.M. 



KEY TO SPECIES OF HIPPO.MEXELLA. 



fZoariuui bilamellar.. __ 2. 



l.jZoarium uuilaruellar 5. 



IZoarium incrusting 10. 



[Orifice elliptical, spines__ __3. 



"'|Orifice uouelliptical exteriorly, few or no spines. _. __4. 



[Very small, transverse, lateral avicularia __ff. transversata. 



'[Beak of the large avicularia turned toward the bottom __ H. angustaedes. 



Ovicell with two large pores with a small tongue H. capitiniorti^. 



Ovicell with large ribs and large pores H. rotula. 



Ovicell with small, irregular pores H. incondita. 



Ovicell with radial costules and two large pores H. costulata. 



