NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 149 



SO that the bottom of the peristome can be seen. The zooecia are sometimes 

 bordered by a saUent thread (tig. 13). The ovicell is very small (fig. 11). In the 

 the interior the olocyst is perforated by very small pores corresponding to the 

 large widened pores of the superposed tremocyst. 



Occurrence. — Pleistocene: Santa Monica (rare) and Santa Barbara, California 

 (common) . 



Habitat. — Pacific: Coronado Islands (24-29 meters). 



Plesiotypes.— Cut. No. 68052, U.S.N.M. 



Genus PALMICELLARIA Alder, 1864. 



1864. Palmicellaria Alder, Description New British Polyzoa, Quarterly Journal Microscopical 

 Society, newsor. , vol. 4, p. 100. 



The apertura is orbicular, semicircular, or semielliptical. Neither lyrula nor 

 cardelles are present. The ovicell opens in the peristomie. The frontal is a granular 

 pleurocyst, surrounded with areolar pores. The peristomie is much developed. 

 Often an avicidarian mucro partially hides the apertura. 



Genotype. — Palmicellaria elegans Alder, 1864. 



Range. — Miocene to Recent. 



The known species of tliis genus are : 



Palmicellaria elegans Alder, 1864. 



Palmicellaria {Millepora) sZ:f nei Solander, 1786. 



Palmicellaria {Eschara) lorea Alder, 1864. 



Palmicellaria inermis Jxiilicn, 1882. 



Palmicellaria tenuis Calvet, 1907. 



Structure. — -The species of this genus are garnished witli areolar pores and they 

 therefore do not belong to the genus Porella Gray, 1848, as we have limited it. The 

 absence of the IjTula and of cardelles distinguishes it from Smittina. 



Historical.— YoT a long time, on the authority of Waters, the species of this 

 genus have been classed in the genus Porella Gray, 1848, because the known man- 

 dibles are identical. The opercula and mandibles of Palmicellaria shenei Solander, 

 1786, are indeed those of Porella. The mandible of P. lorea Alder, 1864, is also that 

 of Porella, but the operculum is semielliptical and of quite a divergent type from 

 other Porellas. The chitinous appendages of the genotype and of the other species 

 are unfortunately unknown. 



All of the species cited having without exception the same characteristic of 

 calcification, namely, a granular pleurocyst surrounded by areolar pores, we believe 

 that it is necessary to maintain Alder's genus, although it does not appear to us very 

 well marked. 



PALMICELLARIA cf. INERMIS Jullien, 1882. 



Plate 4, fig. 13. 



Our figured specimen is too incomplete to be named with certainty, but we are 

 introducing it to call attention to the genus in the early Miocene. This specimen is 

 deprived of ovicell and its aperture is invisible. It approaches Palmicellaria inermis 

 Jullien, 1882, but it differs from it in its larger micrometric measurements and in its 

 apertura, which does not appear transverse. 



Occurrence. — Miocene (Bowden horizon) : Santo Domingo. 



Plesiotype.—Qfit. No. C86o3, U.S.N.M. 



