17 
NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
Order CHEILOSTOMATA Busk. 
Suborder Anasca Levinsen. 
Division I. MALACOSTEGA Levinsen 
Family ELECTRINIDAE D’Orbigny, 1851. 
Genus ELECTRA Lamouroux, 1816. 
(For description, see Bulletin 106, U. S. National Museum, p. 76.) 
ELECTRA MONOSTACHYS Busk, 1854. 
Plate 29, figs. 1-3. 
I 
1854. Membranipora monostachys Busk, Catalogue marine Polyzoa in British Museum, pt. 2, C’hei- 
lostomata, p. 61, pi. 70, figs. 1-4. 
1859. Membranipora monostachys Busk, Monograph fossil Polyzoa of the Crag, Publications Pale- 
ontographical Society, London, vol. 14, p. 31, pi. 2, fig. 2. 
1880. Membranipora monostachys Hincks, British Marine Polyzoa, p. 131, pi. 17, figs. 3, 4; pi. 18, 
figs. 1-4. 
1889. Membranipora monostachys Jelly, A Synonymic Catalogue of Marine Bryozoa, p. 155 (Cites 
bibliography). 
1896. Membranipora monostachys Calvet, Bryozoaires: Resultats scientifiques de la Campagne du 
“Cauden” dans le Golfe de Gascogne, Annales de l’Universite de Lyon, vol. 26, p. 253. 
1900. Membranipora monostachys Waters, Bryozoa from Franz-Josef Land, Journal Linnean Society 
London, vol. 28, p. 59, pi. 8, fig. 3. 
1904. Membranipora monostachys Calvet, Bryozoen: Ergebnisse der Hamberger Magalhaensiche 
Sammelreise, p. 13. 
1911. Membranipora monostachys Guerin-Ganivet, Bryozoaires de l’expedition des Jacques 
Cartier, Bulletin de l’lnstitut oceanigraphique, no. 207, p. 9. 
1912. Electra monostachys Nordgaard, Revision av Universitetsmuseets samling ar norske Bryo- 
zoer, Kgl. norske Videnskabers Selskabs Skriften, 1911, no. 3, pp. 1-19. 
1912. Membranipora monostachys Osburn, The Bryozoa of the Woods Hole Region, Bulletin Bureau 
Fisheries, vol. 30, 1910, p. 227, pi. 22, fig. 29; pi. 39, fig. 87. 
1914. Electra monostachys Canu, Contribution a l’etude des Bryozoaires fossiles, Les Bryozoaires 
du Stampien, XIV, Bulletin Soci4te Geologique de France, ser. 4, vol. 14, p. 147, pi. 4, 
fig. 1. 
Measurements.— Opesia 
7(0 = 0.26-0.34 mm. 
lo = 0.28 mm. 
Zooecia- 
X2 = 0.40-0.48 
Iz =0.24-0.26 
mm. 
mm. 
Variations .—Our specimens agree with the figures given by Hincks in 1880 and 
by Busk in 1859. The variety with large gymnocyst noted by Waters in 1900 
probably constitutes a distinct species, perhaps identical with Membranipora arcuata 
Canu, 1908, from the Post-Pampean of Argentina. 
This species extends scarcely beyond the Tropics and it has remained fixed in 
the Frigid and Temperate Zones. Its occurrence in the Pliocene of South Carolina 
indicates a great contraction of the equatorial zone and the position of the Tropic 
of Cancer toward the thirty-third parallel. Other species confirm this phenomenon. 
There are 10 tentacles according to Waters. 
Occurrence .—Pliocene (Waccamaw marl): Waccamaw River, Horry County, 
South Carolina (rare). Pleistocene: Santa Barbara, California (very rare); Waies 
Bluff, near Cornfield Harbor, St. Marys County, Maryland (rare). 
