11<) BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



smaller size of these last distinguish it from H. megavlcularia in which the avicu- 

 laria are as large as the zooecia proper. 



Occurrence. Middle Jacksonian (Castle Hayne limestone) : Wilmington, 

 North Carolina (rare). 



roti/pcs.CsA.. No. 63881, U.S.N.M. 



HINCKSINA MEGAVICULARIA Canu and Bassler, 1917. 



Plate 23, fi. 1. 



1917. Hincksiiia megavlcularia CAXU and BASSLER. Synopsis of American Early Tertiar.v 

 Uryozon, Bulletin 90. United States National Museum, ]i. 16, pi. 1, fig. 7. 



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

 distinct, elongated, pyriform, and have a gymnocyst; the mural rim is convex, 

 salient, provided with 1-1 to 20 large, hollow spines. The opesium is terminal, 

 elliptical, or somewhat pyriform. entire; the interzooecial avicularium is large, 

 symmetrical, and has a gymnocyst; its opesium is constricted laterally, probably at 

 the place where the pivot ought to be. 



Measurements. Opesia 



/w>=0.30-0.35 mm. r , . [Z.? = O.GO-0.70 mm. 

 Zooecia 



7 =0.2.3 mm. La \lz=OAO mm. 



Length of avicularia=0.60-0.6o mm. 



Affinities. On account of its large avicularia this species differs considerably 

 from Hincksina parv avicularia, but it approaches the recent //. pyrula Hincks, 

 1881. It differs, nevertheless, in its larger number of spines; unfortunately we 

 are unable to compare the ovicells. 



The specimen figured is very instructive. ( )n a zooecium can be seen the 

 coalescing of opposite spines, giving an aspect like the frontal of Menibraniporella. 

 Many zooecia are regenerated; in one case a normal zooecium succeeds a normal 

 zooecium and a double row of spines results; in another case an avicularium re- 

 places a zooecium; in a third an avicularium again replaces a zooecium, but in a 

 totally inverted position. 



OcctD'/'i /K-I'. Middle Jacksonian (Castle Hayne limestone): Wilmington, 

 North Carolina (very rare). 



Iloloti/pc. Cat. No. C)2rT4. T'.S.X.M. 



HINCKSINA COSTULIFERA. new species. 



Plate 23, figs. 2-r,. 



De>s>'-)''t]~>tifi. The zoarium incrusts oilier bryozoa or creeps over algae. The 

 zooecia are elongated, distinct, elliptical or pyriform with or without a gymno- 

 cyst: the mural rim is convex, salient, ornamented with 13 to 15 areal spines and 

 2 oral spines a little larger. The opesium is elliptical, entire. The endozooecial 

 ovicell is a salient convexity. No interzooecial avicularia. The ancestrula is a 

 small ordinary zooecium. 



. (Ao = 0.34-0.40 mm. . (3=0.48-0.50 mm. 

 Measurements. ( Jpesia 7 .oooecia , 



170=0.20 mm. \ h = 0.28-0.32 mm. 



