NORTH American later tertiary and quaternary beyozoa. Ill 



very irregular. The denticle placed on the pivot of the large avicularia is rather 

 peculiar to this species, but it is not constant; it corresponds perhaps to a particular 

 arrangement of the rachis. The known recent bryozoa never have this arrangement. 

 The nimiber and importance of the avicularia indicate calm waters. 



Occurrence. — Miocene (Choctawhatchee marl) : Jackson Bluff, Ocklocknee River, 

 25 miles southwest of Tallahassee, Florida (rare) . Pliocene ( Waccamaw marl) : 

 Waccamaw River, Horry County, South Carolina (very rare) . 



Cotyfes.—C&t. Nos. 68573, 68574, U.S.N.M. 



GEMELLIPORELLA VORAX, new species. 



Plate 19, figs. 1-9. 

 Description. — The zoarium incrusts shells, oysters, and bryozoa. The zooecia 

 are little distinct, separated by a furrow, irregularly elliptical; the frontal is_ convex, 

 sixrrounded by some large areolar pores which are scattered and covered over with 

 a pleurocyst more or less granular. The apertura is deep, oval, the point below 

 with rimule wide and notched; the peris toniice is semilunar with a proximal mucro 

 more or less developed. The ovicell is convex, little salient, deeply embedded 

 in the distal zooecium; its orifice is very wide and can not be closed by the operculum. 

 On each side of the apertura there is a round avicularium; very frequently the one 

 between them becomes very long and fusiform. 



Measurements. — Apertura], „" „ ' Zooecia , " ' ™™" 



^ ila = 0.08 mm. Us = 0.30 mm. 



Variations. — This species is exceedingly variable and takes the most fantastic 

 aspects. The zooecia are only distinct on the small zoaria or on the margins of 

 the large ones; at the center of the latter they are absolutely indistinct. The 

 ancestrula is a small zooecium; it engenders two distal and four proximal zooecia. 

 There are often interareolar costuJes. The reduction of its zooecial dimensions 

 and the great development of the avicularia seems to indicate that this species 

 required much oxygen. 



It is remarkable that the species has disappeared from the recent Gulf of 

 Mexico after its existence in the same region throughout the Miocene and Pliocene. 



Occurrence. — Lower Miocene (Chipola marl) : Chipola River, Calhoun County, 

 Florida (rare) . Miocene (Duplin marl) : WUmington and Natural Well, 2 miles 

 southwest of Magnolia, Duplin County, North Carolina (common) ; Muldrows Mills, 

 5 miles south of Maysville, South Carolina (rare). Miocene (Choctawhatchee 

 marl) : Jackson Bluff, Ocklocknee River, 25 mUes southwest of Tallahassee, Florida 

 (rare). Miocene (Yorktown formation): Yorktown, 3 miles southwest of Peters- 

 burg, and other localities in Virginia (rare) . Pliocene (Waccamaw marl) : Wacca- 

 maw River, Horry County, South Carolina (common). Pliocene (Caloosahatchee 

 marl) : Shell Creek, De Soto County (rare) , and Monroe County, Florida (common) . 



Cotypes.— Cat. Nos. 68575-68580, U.S.N.M, 



GEMELLIPOREIXA PUNCTATCA Canu and Bassler, 1919. 



Plate 5, figa. 7-9. 

 1919. GemelUporella punctata Canu and Basslek, Biology and Paleontology of the West Indies, 

 Bryozoa. Publications of the Carnegie Institution of Washington, No. 291, p. 92, pi. 5, 

 figs. 7-9. 



Description. — The zoariima is free, cylindrical, bifurcated. The zooecia are very 

 little distinct, elongate, convex ; the frontal is granular and surrounded with areolar 



