KONGL. SV. VET. AKADEMIENS HANnLINGAR. BAND 32. N:0 I. 105 



Tribus III. Pycnolithiiisp n. 



. The charactei's of this tribus are the same as that of the next genus the only 

 one having hitherto been found. 



Gen. Pycnolithus n. 

 (ITux.voi;, dense.) 



The calicle is of the coinmon Heliolitidean type with twelve septa and horizontal 

 tabula?. The coenenchyma is dense, only on the sui'face ornamented by shallow grooves 

 and pits of contorted, lengthened outlines, filled np a little below the surface, so that the 

 whole coenenchymal mäss is thick and compact without any structure, only traversed by 

 the whitish, longitudinal stripes which denote the thecte between the superlicial grooves. 



Pycnolithus hifidus n. 



Pl. XI, figs. 5—9. 



The pol}'parium is disciform with an even surface and immersed calicles. The 

 calicles are small, scarcely one millim. across. On their interiör side there are twelve 

 broad, short, blunt prominences which are homologous with the short septa of several 

 Heliolitidse. They have besides the peculiarity of being bifid through a small indentation 

 along their margin. In a longitudinal section they are not visible. The interiör of the 

 calicular tube is partitioned by i-egular, somewhat distantiated tabula^, a little concave 

 and through låter deposits much deformed. The theca is of unusual thinness and is 

 discernible only as a narrow white lining around the aperture of the calicle. The coenen- 

 chyma consists near the surface of narrow, vermiform grooves, separated through thick 

 partition walls. These cavities are very shallow and extend only to a tritling depth below 

 the surface, giving to this in a longitudinal section (pl. xi, tig. 8) a crenulated appearance. 

 Below, there is all a compact mäss of a grayish tint, finely granulated, traversed longi- 

 tudinally by threadlike, white lines being the narrow thecas, surrounding the grooves of 

 the surface. In a transverse section they are seen as a net of white lines including the 

 grayish mäss (figs. 6 — 7). 



This interesting Heliolitid was found in a detached piece on the shore near Wisby 

 amongst other Gotland fossils and the appearance of the rock to which it is adhering, 

 makes it highly probable that it has been deinved from some of the lowest beds, the 

 Stricklandinia bed (b) or the next (c). 



