118 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



OGIVALINA EXIMIPORA Canu and Bassler, 1917. 



Plate 23, figs. 6, 7. 



1017. Ogivalina eximipora CANU and EASSLER, 1917, Synopsis of American Early Tertiary 

 ( 'heilostonie Bryozoa, Bulletin 96, United States National Museum, p. 17, pi. 2, fig. 1. 



Description. 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 thread-like 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 interopesial, triangular, relatively 

 small, and without pivot. 



. (A0=0.75-O.SO mm. . \ Lz =1.20-1. 25 nun. 



Measurements. Upesia , -,, Xiooecia \, A OA 



[(o=0.o5-0.iO mm. (3=0.80 mm. 



Length of avicularium =0.40 mm. 



Variation-?. 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 proxi- 

 mal corners of the said zooecium. This anatomical feature appears to us to have 

 more importance than the absence of the onychocellarium. 



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

 Lenuds Ferry, South Carolina (rare) ; Eutaw Springs. South Carolina (very rare) ; 

 Rich Hill, Crawford County. Georgia (very rare): 



Cofypcs.Czt. Nos. 63884, 62875. U.S.X.M. 



OGIVALINA ELONGATA. new species. 



IMate 23, fig. S. 



Description. The zoarium incrusts other bryozoa. The zooecia are elongated, 

 distinct, elliptical, slightly nan-owed in the rear: the mural rim is thin, smooth, 

 convex, salient, and encompasses the entire zooecium. The opesium is elliptical: 

 the cryptocyst is flat, distinct from the mural rim, granular on the surface, and 

 finely denticulated on its distal edge. The ovicell is a small distal swelling. 



. |A0=0.35 mm. . (Zs=0.55-0.50 mm. 



Measurements. Opesia 7 AO ,AO- Zooecia, 



(Z<?=0.22-0.25 mm. \lz= 0.35-0.45 mm. 



, 

 \lz= 0.35-0.45 mm. 



Variations. The feature which is very characteristic in this species is the 

 more distinct separation of the mural rim and cryptocyst tlinn in Ogivalina e.x- 

 imipora, where it is the mural rim itself which is enlarged into the cryptocyst. An- 

 other important difference is in the symmetry of the opesium, which is one of the 



