766 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Affinities. — The o vice] led specimen (fig. 4) bears two ovicells symmetrically 
placed to the right and left of the zoarium. 
This species differs from Pleuronea alveolata in the fibrous aspect of the basal 
lamella and in the different position of the ovicell. 
It differs from Pleuronea ( Idmonea ) fenestrata Busk, 1859, in its much smaller 
tergopores and its smaller micrometric measurements. 
Occurrence. — Midwayan (Clayton limestone) : Luverne, Crenshaw County, 
Alabama ( common ) . 
Ootypes. — Cat. No. 65244, U.S.N.M. 
PLEURONEA FENESTRATA Busk, 1859. 
Plate 114, figs. 1-1S. 
1859. Idmonea fenestrata Busk, A Monograph of tlie Fossil Polyzoa of the Crag, Publi- 
cations of the Palaeontographical Society of London, vol. 14, p. 105, pi. 15, fig. 6. 
1S77. Idmonea fenestrata Manzoni, I Briozoi fossili del Miocene d’ Austria ed Ungheria ; 
Part 3, Denkschriften der math, natnr. Classe der k. Akademie der Wissenschaften 
Wien, vol. 38, Ahth. 2, p. 6, pi. 4, fig. 14. 
18S0. Idmonea fenestrata Seguenza, Le formazioni terziarie nella Provincia di Reggio 
(Calabria), Reale Accademie dei Lincei, Memoire della Classe di Scienze Fisiche 
matematiche e Naturali. Roma, ser. 3, vol. 6, p. 132. 
1897. Idmonea fenestrata Neviani, Coral lari e Briozoi neogenici di Sardegna, Bolletino 
dell Societa Geologica Italiana, Roma, vol. 15, p. 595 (27). 
Description . — The zoarium is free, arborescent, bifurcated or reticulated with 
oval section, idmoneiform. The fascicles are quite salient, uniserial, scattered, 
alternate, adjacent to the median crest. They bear at the maximum five tubes. 
The tubes are salient, visible exteriorly, flat, separated by a salient thread ; the 
peristome is thin and rectangular. The basal lamella bears a thick layer of tergo- 
pores almost as large as the tubes; their orifice forms regular, longitudinal lines 
or a complicated network. The ovicell is large, convex, porous; it bears tuberosi- 
ties arranged in quincunx. 
(Peristome 0.12 mm. 
Measurements .— j D i stance between the fascicles 0.24-0.30 mm. 
Variations . — The basal side of this species is quite variable; there is not a 
single specimen exactly like the others. The orifices of the tergopores are large 
(fig. 4) or small (figs. 5, 7, 13) in quincunx or in lines; they even overturn the 
frontal on the old zoaria (figs. 12, 16) ; those which are arranged in longitudinal 
series are the most frequent. The tergopores sometimes occur at the base of pseudo- 
sulci. 
Fortunately the frontal is more regular (figs. 3, 14) and permits the determi- 
nation more easily. 
The ovicell of this species is quite variable in its form, dimensions, and posi- 
tion. In our studies on the cyclostomatous bryozoa we figure some interesting 
variations which show that the ovicell is as polymorphic as in the genus Tubuli- 
pora itself. 
