EARLY TERTIARY CHEILOSTOME BRYOZOA. 11 



lateral septulae. Triangular, interopesial hollows having peculiar 

 walls. 



Genotype. — Memhranipora lacroixii Authors. Range: Cenoma- 

 nian-Recent. 



The American Eocene species are C onopeum, lacroixii Busk, 1852, 

 from the Claibornian and Lower Jacksonian of Mississippi, C. 

 hookerl Haime, occurring in the Lower Jacksonian of Mississippi 

 and seven new species ranging from the Midwayan to the Jacksonian. 



Genus MEMBRANIPORINA Levinson, 1909. 



1909. Membraniporina Levinsen, IMorphological and Systematic Studies on 

 the Cheilostomatous Bryozoa, p. 145. 



Membranipores exhibiting neither ovicells nor avicularia. 



M embranijyorlna is not a true genus but is simply an artificial 

 grouping proposed by Levinsen for the reception of species incom- 

 pletely described or of which we have insufficient information to 

 place them more definitely. 



The American species of Memhraniporina are Membraniporina 

 riTmilata Ulrich, 1901, from the Aquia formation of Maryland, M. 

 laxa Reuss, 18G9, from the Claibornian of Alabama, and five new 

 species from the Midwayan, Jacksonian, and Vicksburgian of the 

 Southern States. The following new species is interesting because 

 of the peculiar, calcified tubule in the zooecium. 



MEMBRANIPORINA BENJAMINI, new species. 



Plate 1, fig. 1. 



Description. — The zoarium is incrusting. The zocecia are large, 

 elongate, elliptical, and distinct; the mural rim is rounded, smooth 

 everywhere of equal width. The opesium is median, elliptical, en- 

 tire. In the vicinity of the septulae there is often an incomplete 

 small canal. 



Measurenfients! — Opesia , „ ' 



^ [ Zc>= 0.30 mm. 



. [ Zs=0.65-0.70 mm. 

 Zooecia , r^ a^ r, ^r 



1 7s =0.40-0.45 mm. 



A-ffinities. — Only the fragment figured, which is of considerable 

 interest, has been found. In the proximal part of the zooecium in 

 front of each septula, there is a sort of incompletely calcified tubule 

 serving probably to protect the mesenchyme filaments which pass 

 from one zooecium to another. 



1 In the citation of measurements, Jio Is tbe length and ?o the width of the opesia, Lz 

 and Iz similarly the length and width of the zooecia, Lv and Iv the same for the vibraculum, 

 Lon and Jon for the onychoeellaria, ha and 7a for the apertiira, etc. 



