142 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
ALDERINA IRREGULARIS Smitt, 1872. 
1872. Membranipora irregularis Smitt, Floridan Bryozoa, Kongl. Svenska Vetenskaps- 
Akademiens Handliogar, vol. 10. No. 11. p. S, pi. 11, fig. 63. 
1914. Membranipora irregularis Osbukn, The Bryozoa of the Tortugas Islands, Florida, 
Publication Carnegie Institution of Washington, No. 182, p. 194. 
Not D'Orbigny, 1S39, Waters, 1904, Busk, 1861, Manzoni, 1S75. 
Observations. — We owe to the kindness of Doctor Osburn a very complete, 
superb specimen of this interesting species, and we are able to supplement the 
observations which are indispensable for its classification. The ovicell is transverse 
and formed of two calcified layers; the superior one is very finely granulated, 
incomplete, surrounding an area which is irregular and more or less linear. It is 
hyperstomial and opens by a large special orifice which the opercular valve never 
closes. The latter is bordered by 
a very thick sclerite. The mural 
rim is granular and enlarged at 
the base. This is a very well 
characterized species of Alderina. 
Measurements.- — [A<?=0.34 mm. 
Opesia,Z<?=0.20 mm. 
[£.3=0.40-0.56 m m. 
1 1, 3=0.30-0.40 mm. 
Zooeoia 
Fig. 36. — Genus Alderina Norman, 1903. 
A, B. Alderina imbellis Hincks, 1860. A. Zooecia, X 25. 
(After Hincks, 1880.) B. Sketch showing dietellae, X 47. 
(After Levinsen, 1894.) 
C . Alderina solidula Hincks, 1860. A young zooecium at 
the edge of a zoarium. (After Norman, 1903.) 
Affinities. — This species is the 
equatorial representative of the 
boreal Alderina imbellis Hinck, 
1860. It differs from it in its 
transverse and nonelongated ovi- 
cell and its irregularly linear and 
nonrectangular ovicellarian area. 
Smitt in 1872 identified it 
with M embr a nip ora irregu- 
laris D’Orbigny, 1839. The 
type is no longer to be found at the Museum of Natural History of Paris. The 
figure does not show an ovicell ; as the mural rim is smooth and is not enlarged at 
the base, it certainly represents a different species from that of Smitt. Waters in 
1904 1 found it almost in the same regions; he figured its ovicell but without giv- 
ing its nature; the micrometric dimensions are much larger, to wit: Ao=0.60 mm., 
lo= 0.32 mm., £3=0.80 mm., Zs=0.44 mm. If it should be proved that this is an 
Alderina it would be necessary to rename Smitt’s species of much later date. 
Busk in 1861 2 thought he had found D’Orbigny’s species in the Madeira 
Islands. The figure which he gives is in effect very close to that of the French 
author; the mural rim is not enlarged at the base; this is, therefore, not the species 
1 1904. Waters, Bryozoa, Result. Voyage Belfiica Zool., p. 31, pi. 11. fig. 6. 
2 1861. Busk, Description of new Polyzoa, collected at Madeira in 1859 and 1860, Quarterly Journal 
Microscopical Science, new ser., vol. 1, p. 77, pi. 33, fig. 3. 
