578 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



rocyst. The apertura is hidden at the base of a- large peristomie; it is transverse 

 (interior) and formed of a semielliptical anter separated by two small cardelles 

 from a somewhat concave poster; the peristome is very salient, thin; its distal 

 part supports eight spines ; its proximal part bears a wide, very salient mucro per- 

 pendicular to the zooecial plane or depressed on the frontal. The ovicell is small, 

 salient, globular, smooth; it is hyperstomial and recumbent. 



| /ta=0.12 mm. f 2=0.80-1.00 mm. 



Measurements. Apertura i, Zrooecia,, _ -,. ft QA 



Uo=0.14-0.18 mm. I Iz=0.i0-v.b0 mm. 



Affinities. This large and beautiful species has been known for a long time. 

 The transversal schematic section of a zooecium given by Gabb and Horn is per- 

 fectly exact. The labial mucro is placed in such a position that our photographs 

 can not show their important saliency. 



The operculum may never close the ovicell. 



This species differs from Pcriyastrc-Tla semierecta Koschinsky, 1885. in its 

 larger dimensions (Ls=0.80 and not 0.70 mm.) and the different disposition of 

 the labial mucro. 



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

 near Lenuds Ferry. South Carolina (very rare). 



Upper Jacksonian (Ocala limestone) : West bank Sepulga River, Escambia 

 County, Alabama (rare). 



Pte&iotypes.CnA. No. 04195, TT.S.N.M. 



PERIGASTRELLA OSCITANS. new species. 



Plate 72, figs. 15-18. 



Description. The zoarium incrusts shells, often over a very large surface. 

 The zooecia are distinct, elongated, elliptical; the frontal is convex and surrounded 

 by a line of round or triangular areolae; it is formed of a granular pleurocyst. 

 The apertura (interior) is oblique, transverse, trapezoid; the peristomie, rather 

 deep, often bears two or three very prominent denticles; the peristome is thin, 

 salient, complete; it bears six spines on its distal part and the proximal part is 

 a wide salient mucro. erect, and partially hiding the apertura. The ovicell is 

 small, transverse, salient, very widely open ; its pleurocyst does not entirely cover 

 the olocyst, thus leaving a very apparent frontal area. 



[Art 0.08 mm. . fz= 0.60-0.70 mm 



Measurements. Apertura \, Aooeciai, OA ... 



(la=O.OS-0.lO mm. 1/2=0.30-0.40 mm. 



Variations. It is difficult to find good specimens of this species, for they are 

 easily altered by fossilization ; the apertura is always more or less closed by the 

 calcareous deposit. AA T e have succeeded, however, in preparing a superb specimen 

 (fig. 15) in the vicinity of the ancestrula; the areolae are there quite small and the 

 labial mucro is much attenuated. The more habitual aspect of the species is that 

 of our figure 10. 



