NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 165 



Affinities. — This species differs from Metrarahdotos coUigatum and from Metrarah- 

 dotos lacrymosum in its much larger zoaria and in its larger zooecial dimensions 

 (is > 0.70 mm.). It differs from Metrarahdotos moniliferum Milne-Edwards, 1838, 

 in the absence of a pseudolyrule in the peris tomice. 



The two large oral avicularia occur like two lateral ears; they are rather 

 constant but often are diminished and partially buried by the activity of the cal- 

 cification. In some rare cases they are replaced by a single supraoral avicularium. 



Occurrence. — Pliocene (Waccamaw marl) : Waccamaw River, Horry County, 

 South Carolina (common) . Pliocene (Caloosahatchee marl) : Shell Creek, De Soto 

 Cc^unty (very common), and Monroe County, Florida (very common). 



Cotypes.^C&t. Nos. 68679, 68680, U.S.N.M. 



Genus fflPPALIOSINA Canu, 1918. 



1918. Hippaliosina Canu, Hippaliosina, un nouveau genre de Bryozoairea, Bulletin de la Soei6t6 

 g^ologique de France, ser. 4, vol. 18, p. 88. 



The ovicell is endozooecial. The apertura is elongate, elliptical, divided into 

 two parts by two triangular cardelles; the poster is smaller than the anter. The 

 frontal is a granular pleurocyst surmounting an olocyst perforated laterally by 

 areolar pores. There are usually two avicularia on each side of the apertura. 



Genotype. — Hippaliosina (Escharella) rostrigera Smitt, 1872. 



Range. — Rupelian-Recent. 



The family Hippopodinidae is perhaps not a natural one, because the larva is 

 not known. We classify here all the species in which the ovicell is endozooecial. 

 Nevertheless, the genus Hippaliosina is undoubtedly very close to Hippopodina 

 Levinsen, 1909, and Cheilopora Levinsen, 1909, which are characteristic of the 

 family. It differs solely in the function of calcification; the tremocyst is replaced 

 by a granular pleurocyst, accompanied by lateral areolar pores. Metrarahdotos 

 Canu, 1914, presents also lateral areolar pores and a pleurocyst, but the hydro- 

 static function operates here through a vanna and not a rimule; moreover, the 

 ovicells are totally different. 



In addition to two new recent species from the Philippine Islands, the following 

 species belong to this genus: 



Hippaliosina (Lepralia) depressa Busk, 1852. Recent. 



Hippaliosina (Escharella) rostrigera Smitt, 1872. Recent. 



Hippaliosina (Lepralia) clavula Manzoni, 1871. Helvetian. 



Hippaliosina hrevirostris Canu, 1918. Recent. 



Hippaliosina (Hemeschara) sandbergeri Reuss, 1869. Rupelian, Aquitanian. 



Hippaliosina laxipora Canu, 1918. Miocene. 



The genotype Hippaliosina rostrigera has been dredged near the twenty-second 

 parallel a slight distance from the Tropic of Cancer, where it appears to have found 

 its best conditions for existence. We can infer that the fossil species have lived 

 under similar conditions and that their presence indicates likewise the vicinity of 

 the Tropic. In tliis case their geologic distribution would indicate the displacement 

 of this line through the ages, and consequently the contraction of the equatorial 



