NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 73 



Fig. 12. — Genus Ilemiseptella Levinsen, 1919. 



Figs. A-N. Hemiseptella labiata Busk, 1884. 



A. A branch of the form Vincularia elegans (after D'Orbigny, 1839). B. A branch from Cape 

 Horn, X 12. A few minute denticles or hooks occur on the border of the opesium. C. Several zooecia 

 of the type of Vincularia elegans preserved at the Museum of Paris. A growth from each side forms a 

 calcareous bridge over the opesium. It is placed under the membraneous ectocyst. D. A calcined 

 zooecium of a specimen from the Atlantic (Challenger collection), X 25. E. Transverse section, X 25. 

 F. Calcareous section diagonally through a zooecium, thus showing the projecting rosette plates (sep- 

 tulae), X 25. G. Section through the dietellae, X 250. H. Diagrammatic section showing the position 

 of the' septulae, X 25. I. Transverse, decalcified section, X 25. J. A branch, natural size (after 

 D'Orbigny, 1839). K. Section in the zooecia, X 25. Besides the lip which projects upward, the front 

 wall of the zooecium is directed downward thus contracting the zooecium near the aperture. (Figs. 

 D-H, K, (after Waters, 1889). L. Transverse section in operculum, X 85 (B, C, I, L, after Waters, 

 1895). M., N. Operculum (after Busk 1884). 



Fig. 0. Hemiseptella denticulata Smitt 1872. A zoarium from Florida. The unshaded zooecia 

 are covered by the ectocyst. They show the chitinous arch of the opercular valve. 



Fig. P-S. — Hemiseptella steganoporoides MacGilU\Tay, 18S1. P. A zoarium, natural size, from 

 Prince Edward Island. Q. Zooecia with their opesiular in dentations and occasionally the bridge, X 25 

 (forma Vincularia gothica). R. A zooecium showing the sutures between the three processes and the 

 a^'icularium (after Waters, 1889). S. Operculum, X 85 (figs. P, Q and S, after Busk, 1884). 



Figs. T-\ .—Hemiseptella michaelseni Calvet, 1904. T. Zooecia, X 25, showing the three groups of 

 spinous processes bordering the opesium. U. A zooeciimi covered by its membranous transparent 

 ectocyst under which the spinous processes are seen. V. Operculum, X 85 (T-V, after Calvet, 1907). 



This species is much smaller than Hemiseptella rectangulata, in which the form 

 of the zooecia is identical but which is deprived of tubercles. 



Occurrf ?!ce.— Pleistocene: Simmons Bluff, Yonges Island, Charleston County, 

 South Carolina (rare). 



Hohtype.— Cut. No. 68492, U.S.N.M. 



HEMISEPTELLA FISTULA Lirich and Bassler, 1904. 



Plate 14, fig., 9. 

 1904. Membranipora fistuluI'LRiCH and Bassler, Bryozoa: Maryland Geological Survey, Miocene, 

 p. 413, pi. li2, fig. 5. 



The original description is as follows: 



Zoarium so far as observed forming small, hollow, subcylindrical stems, about 1.5 mm. in diameteri 

 composed of twelve to fifteen longitudinal rows of zooecia. Walls about as wide as the 

 zooecial openings, obtusely carinate, the carinae between the ends of the cells high and 

 bent forward so as to impart a slightly imbricating appearance to successive cells. Opesial 

 opening elongate elliptical; immediately behind it a minute pore is occasionally notice- 

 able. Measuring longitudinally about 8 zooecia in 5.0 mm. No avicularian nor \-ibracular 

 cells observed. 



The original description of tliis slender rod-like bryozoan gives an adequate 

 idea of the species, of which unfortunately no more specimens have been discovered. 

 We reproduce a new illustration of the type specimen which shows spines irregularly 

 distributed on the proximal border of the opesium, thereby causing the species to 

 be referred to Hemiseptelta. 



Occurrence. — Miocene (St. Mary's formation): St. Mary's River, Maryland 

 (very rare). 



Holotype. —C&t. No. 68493, U.S.N.M. 

 12184— 23— Bull. 125 6 



