70 BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 



One must not confuse the spinous processes or spinules with the spines. Their 

 structure is not similar and their physiologic role is absolutely distinct. The spinous 

 processes are here only internal apparatus for support, probably intended to limit 

 the movements of the hypostege. 



The large retractor muscle of the polypide is inserted in a corner of the zooecium 

 as in Onychocella, Odontionella, and Steganoporella. It results in a great dissymme- 

 try of the opesium especially on its proximal border. 



The known species of this genus are : 



Hemiseptella {Vincidaria) laiiata Busk, 1884. 



Hemiseptella (Vincvlaria) steganoporoides Goldstein, 1882. 



Hemiseptella {Thalamoporella) michaelseniCalvet, 1904. 



Hemiseptella (Bijlustra) denticulata Smitt, 1872. 



Hemiseptella { ilemhranipora) tenuis Desor, 1848. 



Hemiseptella {Memhranipora) lacinia Tuomey and Holmes, 1857. 



Hemiseptella {Memhranipora) minor Canu, 1908 {M. sulcata, var. minor Canu). 



HEMISEPTELLA LATA Car.a and Bassler, 1919. 



Plate 2, fig. 4. 

 1919. Hemiseptella lata Canu and Bassler, Geology and Paleontology of the West Indies, Bryozoa 

 Publication of the Carnegie Institution of Washington, No. 291, p. 85, pi. 2, fig. 4. 



Description. — The zoarium incrusts fronds of the bryozoan Metrarahdotos. The 

 zooecia are distinct, little elongated, wide, subrectangular; the mural rim is thin. 

 The opesium is elliptical or orbicular, never symmetrical; the cryptocyst is short, 

 little deep, irregular; the opesiular indentations are represented by two lateral dis- 

 symmetric concavities and are often separated by a wide and serrate denticle. 



,, . ^ • f^o = 0.30mm. „ . fi2 = 0.42 mm. 



Measurements. — Upesia , « oo r. on Ziooecia ■, „ on « or, 



^ 1 40 = 0.22-0.30 mm. [ 42 = 0.30-0.32 mm. 



Affinities. — It is always difficult to characterize a species from the study of a 

 single specimen. Exteriorly the zooecia have the form of certain zooecia observed 

 in Acanthodesia savartii Savigny-Audouin, 1826; it difi'ers from it in its nonsymmetric 

 opesium and in two opesiular sinuosities. 



This species differs from Bijlustra savarti Smitt, 1872, which is not perhaps the 

 species of Audouin, in the more constant development of its cryptocyst and in the 

 nature of its zoarium, which does not incrust algae. The proximal denticle has been 

 clearly observed on tliree zooecia. 



Occurrence. — Lower Miocene (Bowden horizon) : Cercado de Mao, Santo 

 Domingo (very rare) . 



Holotype.—C&i. No. 68498, U.S.N.M. 



HEMISEPTELLA? LACINIA Tuomey and Holmes, 1857. 



Plate 14, fig. 10. 



1857. Memhranipora lacinia Tuomey and Holmes, Pleiocene Fossils of South Carolina, p. 14, pi. 4, 

 fig. 10. 



We liave been unable to find any specimens corresponding to the figure of 

 Memhranipora lacinia, which, moreover, is somewhat confusing, although probably 

 indicating the genus Hemiseptella. We reproduce the original figure in the hope that 

 some future student wiU rediscover the species. 



Occurrence. — Miocene?: Smith's, Goose Creek, South Carolina. 



