598 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Genus SCHISMOPORA MacGillivray, 1888. 



1888. Schismopora MACGILLIVRAY, Bryozoa in McCoy's Prodroums of the Zoology of Vic- 

 toria, vol. 2, dec. 17, p. 253. 



The ovicell is perforated. The frontal is smooth. The apertura bears a 

 proximal rimule. No spines. 15-20 tentacles. 



Genotypes. Schismopora (GeUepora) coronopus S. Wood, 1850. and Schis- 

 mopora (Cellepora) pumicosa Busk, 1854. 



UniHje. Jacksonian Recent. 



Historical. This is the Pumicosa group of Waters, for which he has always 

 preserved the name of Cellepora until 1913, when certainly it was by error that he 

 called it OstMmosia. The latter genus of Jullien is perfectly limited as he described 

 it in 1904 and 1909. The genus Schismopora MacGillivray. 1888, has a much more 

 general meaning, since he applied it to all the Cellepores with proximal rimule. 

 We preserve it, however, with a more restricted meaning so as not to create a new 

 name. 



Certain recent species classified in this genus are provided with tremopores; 

 it will be necessary to create a special genus for them. 



SCHISMOPORA GLOBOSA. new species. 



Plate 75, figs. 7-15. 



Description. The zoarium is massive, globular, measuring as much as 18 milli- 

 meters in diameter. The superficial zooecia are distinct, little erect, irregularly 

 ovoid ; the frontal is smooth and convex and bears an avicularium as large as the 

 apertura. The apertura is oval and garnished with a wide triangular rimule. The 

 deep zooecia are visible only through their apertura. The incomplete zooecia are 

 rare. No interzooecial avicularium. 



rA=:0.15min. 

 Measurements. Apertura , 



[ta==0.10 mm. 



Variations. The frontal avicularium is almost always broken; it leaves a wide 

 cicatrix of little depth (fig. 11). 



The. transversal section (fig. 13) perfectly oriented is very instructive: it is 

 the perfect type of the Celleporid accumulation. Above each zooecium there is 

 a small triangular chamber which appears to correspond to the frontal avicularium ; 

 the plates of these small chambers unite two by two, outlining the zooecial contours. 

 The skeletal tissue is an olocyst whose elements are scattered or piled together 

 (fig. 14). 



Affinities. In its large zoarium and its frontal avicularium this species much 

 resembles Holoporella (jlomerata Gabb and Horn, 1862. It differs from it in the 

 different form of its apertura, in the absence of areolae, and its very little elevated 

 zooecia. 



Occurrence. Lower Jacksonian (Mooclys marl) : Jackson. Mississippi (com- 

 'mon). 



Cotypes.C**,. No. 64213, U.S.N.M. 



