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BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
by true perforations called opesiules. The semi-circular aperture has generally 
a more or less strongly chitinized (or calcareous), simple operculum, more seldom 
an opercular valve. Avicularia present. 
Historical . — The family Microporidae as delimited by Hincks and by Jullien 
does not appear very natural because the ovicell system has not been considered ; 
indeed Levinsen in 1909 made some modifications. 
The family may be made more exact by including in it only those genera having 
an endozooecial ovicell. There is no important difference between the Micro- 
poridae and the Onychocellidae ; the onychocellaria simply disappear or are re- 
placed by the avicularia. 
As Canu in 1900, 1 has demonstrated, the replacement of the onychocellaria by 
avicularia is constant in the general line of descent. It is simply adaptation to new 
conditions of existence. 
In our opinion, the Onychocellidae and Microporidae with the Lunulariidae 
form one and the same family for which we have adopted Jullien’s name Opesiu- 
lidae, but have retained the first three mentioned as subfamilies. 
188S. Rosseliana Jui.lien, Mission Scientiflque du Cap Horn, Bryozoaires, vol. 6, p. 78. 
The frontal of the zooecium is a cryptocyst of little depth. The opesium is 
semicircular. The ovicell is endozooecial but prominent. Septulae uniporous. No 
avicularia. 
Genotype. — Rosseliana ( Flustra ) rosselii Audouin, 1826. 
Canu, in 1900, has badly interpreted Jullien’s genus, for the species which he 
considered as Rosseliana are more often typical Onychocella. 
The fossil species are: 
Rosseliana (M embranipora) incompta Eeuss, 1874. Miocene. 
Rosseliana (M embranipora) reussiana Manzoni. 1874. Miocene, Pliocene. 
ROSSELIANA PARVIPORA, new species. 
Plate 82, fig. 16. 
Description . — The zoarium incrusts bryozoa. The zooecia are elongated, dis- 
tinct, separated by a deep furrow; the mural rim is thin, salient, complete, and 
distinct. The cryptocyst is flat, shallow, much larger than the opesium and very 
finely granulated; the opesium is semilunate, transverse, with a proximal concave 
border. The ovicell is endozooecial, protruding, and smooth. 
Affinities . — There is no polypidian convexity in this species and the opesiular 
indentations are only visible on rare zooecia. The ovicelled zooecia have a little 
larger opesium, the breadth of which ranges from 0.12 to 0.14 mm. 
1 Canu, Revision des Bryozoaires du Cr6tac<5 figures par D’Orbigny, Bulletin Soci6t6 G6ologique de France, 
ser. 9, vol. 28, p. 345. 
Genus ROSSELIANA Jullien, 1888. 
Zooecium 
Zs=0.34— 0.36 mm. 
lz= 0.16— 0.20 mm. 
