EARLY TERTIARY CHEILOSTOME BRYOZOA. 17 



OGIVALINA EXIMIPORA, new species. 

 Plate 2, fig. 1. 



DescHjJtion. — The zoarium is composed of one or more lamellae 



and incrusts pebbles or creeps over algae. The zooecia are large, 



elongated, ogival, distinct, separated by a threadlike ridge; the 



mural rim is indistinct, thin, flat, smooth, enlarged at the base into 



a concave, granular, irregular cryptocyst. The opesium is oval, 



entire, unsymmetrical in its proximal part. The endozooecial ovicell 



is a distal convexity, quite apparent. The avicularium is intero- 



pesial, triangular, relatively small, and without pivot. 



, „ . f^(?=0.75-0.80mm. 

 Measurements. — Upesia \ -, ^ k - a ^-a 



^ I ?«9=0.5o-0. ( mm. 



. fZs= 1.20-1.25 mm. 

 Zooecia , ^ ^^ 



Length of avicularium=0.40 mm. 



Variations. — The opesium has little regularity of shape on account 

 of the very irregular development of the cryptocyst itself. Although 

 the latter is generally plainly visible, there are, nevertheless, zooecia 

 which are almost devoid of the cryptocyst. But the most important 

 variation is the unsymmetrical shape of its distal border, a lack 

 of symmetry characteristic of the genus Onychocella. We know 

 that this phenomenon is occasioned by the obliquity of the polypide 

 in the zooecium by reason of the attachment of the retractor muscles 

 in one of the proximal corners of the said zooecium. This anatomical 

 feature app)ears to have more importance than the absence of the 

 onychocellarium. 



Occurrence. — Middle Jacksonian: Wilmington, North Carolina 

 (rare). 



Near Lenuds Ferry. South Carolina (very rare). 



Eich Hill, Crawford County, Georgia (very rare). 



Type.—Qid. No. 62575, U.S.N.M. 



MEMBRENDOECIUM, new genus. 



(Abbreviation of Membranipore with endozooecial ovicell.) 



Ovicell endozooecial. Small simple interopesial avicularia. Die- 

 tellae present. No spines. 



Genotype. — AmpMblestrum papillatum Busk, 1884. 



MEMBRENDOECIUM PYRIFORME, new species. 



Plate 2, fig. 2. 



The zoarium incrusts bryozoa or small shells. The zooecia are 

 very elongate, oval, distinct, and have a gj'^mnocyst ; the mural rim is 



52091°— 17 2 



