NORTH AMERICAN EARLY TERTIARY BRYOZOA. 309 



is semilunar; the distal part is bordered by a very thin, incomplete peristome. 

 There are one or two small, triangular, transverse, oral avicularia touching each 

 other at their tips. 



<ha=0.0i> mm. . \ Ls=0.6Q mm. 



Measurements. Aperture i, . , Zooecia , _ on 



\la=Q,llmm. 1/2=0.30 mm. 



Affinities. All of the zooecia are not provided with the characteristic collar 

 which arises from the more or less complete union of the first three pairs of costules. 

 The number of pairs of costules varies from 12 to 17. 



Only a few specimens have been found, none of which shows an ovicell. The 

 quadriserial zoarium and the costules with lumen pores are the only reasons we 

 have for classifying this species in CorbuHpora, a genus which must be considered 

 ns inadequately described. 



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

 Carolina (rare). 



Holotype.Cai. No. 64085. U.S.N.M. 



Genus ACANTHOCELLA Canu and Bassler, 1917. 



1917. Acantkocella CANU and BASSLER, Synopsis of American Early Tertiary Oheilostome 

 Bryozoa, Bulletin 96, United States National Museum, p. 35. 



The costules bear a row of very prominent lumen pores and are separated 

 by lacunae of greater or less size. The aperture is semilunar. The ovicell is 

 hyperstomial and its orifice is not in contact with the operculum. 



Genotype. Cribrilina tubulifcra Hindis, 1881, from Australian seas. 



Range. Jacksonian-Recent. 



ACANTHOCELLA EKINACEA Canu and Bassler, 1917. 



Plate 43, figs. 10-13. 



1917. Acanthocella crinai-fu- (.'AM and BASSLKR, Synopsis of American Early Tertiary 

 Bryozoa, Bulletin 96. United States National Museum, p. 36, pi. 4, fig. 1. 



Description. The zoarium incrusts shells and bryozoa or creeps over algae. 

 The zooecia are distinct, very slightly elongated, subcircular; the frontal is very 

 convex; the costules are thick, separated by the lacunae and ornamented by three 

 very prominent, hollow spines corresponding to the lumen pores. The aperture 

 is semilunar with a straight proximal border; the peristome is distal and bears 

 four large, hollow spines. The ovicell is hyperstomial, buried in the distal zooecia, 

 globose, not closed by the operculum. ornamented with small, remote punctations. 



,, ;/m=0.09mm. . (.3=0.75-0.80 mm. 



Measurements. Aperture , Zooecia, 1 , 



/ = 0.11-0.12 mm. [7,;=0.50-0.6o mm. 



Variations. The sharp points which decorate this species give it the spinous 

 aspect of a hedgehog. It is very variable in its micrometer dimensions and its 

 gemmation ; the zooecia are oriented in the most unexpected and divergent manner. 

 The costules are separated first by an initial slit (fig. 13) hidden and almost ver- 



