NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 165 
Affinities. —This species differs from Metrarabdotos coUigatum and from Metrarab- 
dotos lacrymosum in its much larger zoaria and in its larger zooecial dimensions 
(Lz >0.70 mm.). It differs from Metrarabdotos moniliferum Milne-Edwards, 1838, 
in the absence of a pseudolyrule in the peristomice. 
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 
County (very common), and Monroe County, Florida (very common). 
Cotypes.— Cat. Nos. 68679, 68680, U.S.N.M. 
Genus HIPPALIOSINA Canu, 1918. 
1918. Hippaliosina Cantj, Hippaliosina, un nouveau genre de Bryozoaires, Bulletin de la Soci6te 
geologique 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. Metrarabdotos 
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 brevirostris 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 this case their geologic distribution would indicate the displacement 
of this line through the ages, and consequently the contraction of the equatorial 
