EARLY PALEOZOIC BKYOZOA OF THE BALTIC PROVINCES, 



247 



LIOCLEMA VETUSTUM, new species. 



Text fig. 141. 



Zoarium consisting of small, irregular patches, less than 0.5 mm. 

 in thickness, growing upon foreign objects. The type-specimen, 

 from which the figured thin sections were prepared, is incrusting 

 an Orthoceras, while the example shown in figure 141 a, is growing 

 upon the cystid Echinos'pherites. The surface is conspicuously 

 smooth and shows no distinctly marked clusters of larger zooecia 

 or mesopores. The zooecial apertures are quite small and somewhat 

 elongate, averaging 0.3 mm, in their longer diameter, with four to 

 five in 2 mm,; small acanthopores, in number about three to a 



d 



^M^^^,^^-- 



\ 



Fig. 141.— Lioclema VETUSTtJM. a, a zoakium, natural size, incrusting an Echinospherites; 6, 



TANGENTIAL SECTION, X20, SHOWING THE USUAL ARRANGEMENT OF ZOCECIA AND ACANTHOPORES; C, POR- 

 TION OF THE SAME, X35, WITH THE SIMPLICITY OF WALL STRUCTURE MORE EVIDENT; d, VERTICAL SECTION, 

 X20, EXHIBITING TENUITY OF ZOARIUM. KUCKERS SHALE (02), REVAL AND BARON TOLL'S ESTATE, 

 ESTHONIA. 



zooecium, indent the cavity and cause the petaloid shape of the aper- 

 ture. Mesopores angular and numerous enough to isolate the zooecia; 

 walls of both kinds of cells thin. 



Vertical sections are difficult to secure on account of the thin 

 zoarium, but all of the structure exhibited in several of these is 

 illustrated in figure 141 d. The absence of diaphragms in the 

 zooecia and their abundance in the numerous mesopores are the most 

 noteworthy features. The appearance in tangential sections is 

 practically the same as in views of the surface. 



The delicate incrusting zoarium and the small, petaloid zooecia, 

 isolated by thin-walled, angular mesopores, are so diiferent from other 

 Ordovician bryozoans that comparisons are unnecessary. 



Occ^^rfe7^ce.— Apparently not uncommon in the Kuckers shale 

 (C 2), Baron Toll's estate, near Jewe, and in the same rocks at Eeval, 

 Esthonia. 



Holotype.—Csit. No. 57320, U.S.N.M. 



