130 BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 



bicular, deeply embedded. The ovicell is globular, smooth, little salient, deeply 



embedded in the distal zooecium. The walls are very thick and perforated by a 



large number of dietellae. The ancestrula is small and reduced to only the aper- 



tura; it emits five zooecia. 



, , , \ha = 0.17 mm. „ . f £2 = 0.50-0.55 mm. 



Measurements. — Apertura , . , „ Zooecia , 



^ lfa = 0.17rmn. [ fe = 0.50mm. 



Variations. — The pleurocyst is detachable by alteration during fossilization 

 (fig. 10). The ancestrula, normal in figure 8, is often covered by the pleurocyst of 

 the adjacent zooecia (fig. 9). Sometimes there are nonoriented zooecia. The 

 calcilied zooecia are provided with tremopores. The structure of the olocyst is that 

 of Cyclicopora. The very thick walls with numerous dietellae characterize this 

 species (fig. 14) ; their number is quite variable from 12 to 20. 



Mucronella laqueata Norman, 1864, presents the same dietellae; it difl^ers from 

 it in its perforated frontal and in the absence of lyrule. 



Occurrence. — Pliocene (Waccamaw marl) : Waccamaw River, Horry County, 

 South Carolina (very common). 



Cotypes.—C&t. No. 68617, U.S.N.M. 



CYCLOCOLPOSA TENUIPARIETIS, new species. 



Plate 21, figs. 1-4. 



Description. — The zoarium incrusts pelecypod shalls. The zooecia are distinct, 

 elongated, elliptical, separated by a deep furrow; the frontal is convex, surrounded 

 by a double row of large, scattered, areolar pores, separated by pleurocystal gran- 

 ules. The apertura is elongate, oblique, elliptical, without cardelles. The ovicell 

 is small, hardly salient, much embedded in the distal zooecium, with frontal smooth 

 and fragile. Rarely a round oral avicularium is present. 



T,r , \ I (7ia = 0.16 nun. „ . fL2 = 0.54-0.58 mm. 



Measurements. — Apertura , „ , ^ Zooecia , 



^ [ia=0.14mm. [ ^2 = 0.46-0.50 mm. 



Affinities. — The presence of the ovicell absolutely disfigures this species; isolated 

 portions of the zoarium containing only ovicelled zooecia can not be determined 

 with certainty. The fragihty of the superior wall is extreme; it does not resist 

 fossilization; it results in a fantastic aspect difficult to comprehend. Exteriorly 

 the pleurocyst is much reduced, and the abundance of areolar pores seems to indicate 

 a tremocyst; the study of the interior does not permit this supposition. 



This species differs from Cyclocolposa perforata in its elongate zooecia and in its 

 very thin zooecial walls. 



Occurrence.— MiocenQ (Duplin marl) : Harvey Mills, Leon County, Florida (rare) . 



Cotypes.~C&t. No. 68618, U.S.N.M. 



CYCLOCOLPOSAC?) SPINITERA, new species. 



Plate 20, figs. 12, 13. 

 Z)escnp<io7i.— The zoarium incrusts oysters. The zooecia are distinct, sepa- 

 rated by a deep furrow, somewhat elongated, much swollen; the frontal is very 

 convex, garnished laterally with a double row of areolar pores and formed of an 

 olocyst supporting a detachable pleurocyst. The apertura is orbicular or some- 

 what elongated and is surrounded by six large hollow spines. The ovicell is hyper- 



