NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 155 



rior) is transverse, subelliptical; the peris tomice bears a rimule spiramen arranged 



between two salient lips. The ovicell is large, convex, smooth, buried in the distal 



zooecium ; its orifice is very large and located in front of the two lips. Many zooecia 



bear a very large avicularium arranged obliquely on the frontal and provided with 



a curved, very salient beak. The zooecia without avicularia bear some small 



scattered pores. 



l/easurewen^s.— Peristomice: Zpe = 0.10 mm. 



„ . fi2 = 0.46-0.60 mm. „ , fL/=2.00mm. 



Zooecia , r, nr, r. o« J^enestrae f, „ „„ „ „^ 



I 43 = 0.20-0.30 mm. | Z/= 0.30-0.75 mm. 



Affinities. — This species differs from PTiidolofora pacifica Robertson, 1908, in 

 the smaller dimensions of its peristomice, which measure more than 0.10 mm. The 

 general aspect is therefore that of bearing apertures much more scattered and in 

 having a peristomice mucli smaller than the zooecial width. 



The micrometric variations are extraordinary. On the same zoarium one may 

 find zooecia 0.50 mm. by 0.20 mm. with zooecia 0.46 by 0.26-0.30 mm. Frequently 

 the peristomice of the ovicelled zooecia is somewhat wider than that of the other 

 zooecia. The vibices are also very irregular; thay are salient, but disappear easily 

 in fossilization. 



Occurrence. — Pleistocene : Dead Mans Island off San Pedro (rare), Santa Monica 

 (common), and Santa Barbara, California (very common). 



Plesiotypes.— Cat. No. 68663, U.S.N.M. 



Genus RHYNCHOZOON Hincks, 1891. 



(For description, see Bulletin 106, U. S. National Museum, p. 506.) 



RHYNCHOZOON VAUGHANI Canu and Bassler, 1919. 



Plate 2, fig. 22; plate 4, figs. 1, 2. 



1919. Rhynchozoon vaughani Canu and Bassler, Geology and Paleontology of the West Indies, 

 Bryozoa, Publications of the Carnegie Institution of Washington, no. 291, p. 94, pi. 2, fig. 

 23; pi. 4, figs. 1, 2. 



Description. — The zoarium is unilamellar. The zooecia are large, distinct, 



hexagonal or claviform; the frontal is smooth, convex, surrounded by a line of 



small scattered areolar pores. The apertura is large, suborbicular, with a wide 



proximal rhnule; the peristomie is deep and widened; the very irregular peristome 



bears some large tubercles; the false rimule is compressed between two large 



tuberosities, one of which bears an oral aviculariima transversely arranged. 



,, ^ A i iha= 1 rj ■ fZ2 = 0.60mm. 



Measurements. — Apertura , . _. Zooecia , _ .. 



^ I (a = 0.20 mm. lZ2 = 0.o0mm. 



Affinities. — This species differs from Rhynchozoon solidum Osburn, 1914, which 

 it much resembles, in its much larger micrometric measurements and in the absence 

 of the small frontal avicularium. 



Occurrence. — Low6r Miocene (Bowden horizon): Cercado de Mao, Santo Do- 

 mingo (very rare). 



Cotypes.—C&t. No. 68664, U.S.N.M. 



