EARLY PALEOZOIC BRYOZOA OE THE BALTIC PEOVINCES. 125 



the illustrated specimen, which appears to be lost, the matter can 

 not be settled. As the basal portion is not shown, the specimen may 

 be a cribrose Stictoporella. 



Description. — Zoarium of narrow, bifoliate branches averaging 

 2.5 mm. in width, inosculating so frequently that a broad frond, with 

 circular or elliptical openings, results. The lower portion of the 

 cribrose zoarium is prolonged into a striated base which is long, nar- 

 row, and pointed in young examples (see fig. 2, pi. 9), and short and 

 more or less rounded in older specimens (see figs. 1, 3, 6, pi. 9). 

 This base articulates with an expanded attachment, as shown in 

 figure 5, plate 9. An average zoarium is 50 mm. in its longer 

 diameter, but larger specimens frequently occur. 



Fenestrules sometimes circular but generally elliptical, and aver- 

 aging 1.5 by 1.8 mm. Although their size and arrangement is more 



.^'.iO'',!- 'mJ' 





n. r\\ 







Fig. 50.— Gbaptodictya peoava. o, tangential section, x20, cutting the striated edge of a beanch 



AND THE ADJOINING ZGCECIA; 6, PORTION OF THE SAME, X40; C, VERTICAL SECTION, X20. WaSSALEM 

 BEDS (D3), UXNORM, ESTHONIA. 



or less irregular, large examples, such as illustrated on plate 9, 

 figure 1, show them disposed in irregular, diagonal, intersecting rows. 

 Zooecia subpolygonal, sometimes subrhomboidal in outline with 

 eUiptical to circular apertures. Interspaces solid with one or two 

 fiine, elevated, papillose lines. Mesopores restricted almost entirely 

 to the edges of the branches, where they form a band around the 

 fenestrules about 0.5 mm. wide. In the lower portion of old zoaria, 

 the fenestrules are often obliterated by the greatly increased width 

 of this band of mesopores. Occasionally a small mesopore or two 

 may be noted among the ordinary zooecia. The articulating pointed 

 base is composed of elongate, narrow, modified zooecia separated 

 by wide, solid interspaces with niunerous elevated lines, this com- 

 bination of elongate zooecia and intervening lines producing the 

 striated appearance. The attached sockethke basal expansion is 



