EAELY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 



87 



CREPIPORA SCHMIDTI, new species. 



Text fig. 26. 



Cfr. Crepipora simulans Ulrich, Geol. Surv. Illinois, vol. 8, 1890, p. 470, pi. 39, 

 figs. 4, 4a; pi. 40, figs. 3, 3a; text fig. 8b, p. 320. 



This species is represented in the collections by only the type- 

 specimen, which is a small, well-developed zoarium incrusting a 

 gastropod. Although variable in this respect, the greatest thickness 

 of this zoarium does not exceed 2 mm. Other specimens undoubtedly 

 will show a greater thickness of the individual crust or will be made 

 up of a number of crusts growing successively upon each other. The 

 maculae are indistinctly marked in the specimen at hand, but, as in 

 similar incrusting species, they are composed of clusters of mesopores 

 surrounded by slightly larger zooecia. Zocecial apertures compara- 

 tively large, direct, rhomboidal to subpolygonal in shape, averaging 

 0.4 mm. in their greater diameter; walls of zooecia thin. Four to 



^'Ofci 



Fig. 26.— Crepipoea schmidti. a, vertical section, X20, sho-wing laminated wall structure; 6, 



TANGENTIAL SECTION, X20, WITH SIMPLE POLYGONAL ZOCECIA AND CRESCENTIC LUNARIA. JEWE LIME- 

 STONE (Dl), Baron Toll's estate. , 



five zooecia may be counted in a length of 2 mm. Lunarium well 

 marked at the surface where it overarches the aperture slightly, 

 occupying about one-fifth of the wall, but not extending into the 

 zocecial cavity. The lunarium is quite distinct in tangential sections 

 but shows no additional characters to those noted at the surface. 

 Vertical sections exhibit a very short, thin-walled, immature zone in 

 which the zooecia are prostrate, and a longer mature region where 

 they are direct and have thicker walls. Diaphragms are thin and 

 very few or wanting entirely. 



• The chief difference between this new species and the closely related 

 American form, Crepipora simulans Ulrich, lies in the size of the 

 zooecia. C. schmidti has four to five zooecia in 2 mm., while C. sijnu- 

 lans has seven in the same distance, thus making the diameter of the 

 former about one-half again as great. Another incrusting Russian 

 species, Crepipora lunatifera, from the Wesenberg formation, differs 

 in having still larger zooecia, more distinct crescentic lunaria mth 

 their ends projecting into the zocecial cavity, and zooecia of an irregu- 

 larly angular shape. 



