KONGL. SV. VET. AKADEMIENS HANDLINGAK. BAND 32. N:0 I. 69 



well as those of the calicles show in sorae places the same microscopic structure of fibrillfe, 

 directed obliquely upwards, as seen in other HelioJitidte and Corals. 



There are some slight variations in the size of the calicles and in the thickness of 

 the coenenchymal walls as seen in specimens from Wisby and Klinte (figs. 5 and 11), 

 though the character in other respects is constant. 



This beautiful species occurs in Gotland in the red layer a near Wisby and in the 

 strata h, c, cl of the same place, in the stratum c at Fröjel and Mölners in Klinte. 



Cosiniolithiis halysitoides n. sp. 



Pl. v, figs. 12—18. 



Polyparj' growing in thin lamellfe of 5 millimeters or less, bearing calicles only on 

 the superior surface, the inferior one covered by a thin wrinkled epitheca having, when 

 seen in a longitudinal section, a finely scrrated edge (hg. 16). Its mode of growth is 

 peculiar. In a specimen fi'om Roma m^^r there are seven thin lamella" above each other, 

 the thickest of 5 mm., but all taken together 45 mm. These lamella? are separated from 

 each other through interspaces now filled with rock. But of these four of the lowest are 

 connected in such manner that the upper one has grown out of next snbjacent, tending 

 obliquely upwards and sending out a new lamella in the same direction. It cannot be 

 doubted ' that the three uppermost lamellfe also were in this manner connected, but the 

 specimen is broken at one end. Only the two uppermost are thus connected. The 

 calicles which attain a diameter of 1 mm are stelliform, the exteriör ^vall being indented 

 and invaginated forming acute angles where it faces the septa. The septa are rather 

 short, continue towards the centre, where they form a sort of an extensive columella of 

 reticulated tissue. The septa are in some calicles sinuous or even as if composed of 

 minute tubuli (fig. 13). In sections of the calicles (figs. 17, 18) the broad septal laminaj 

 form an exteriör zone, showing the oblique arrangement of the elementary fibrillte (fig. 18) 

 and also the scarse concave tabulas which continue into the narrow tubuli formed by the 

 central reticulate meshes. The coenencliyma consists of two sets of tubuli one larger, of 

 irregular oval shape with dense walls, and in these walls there are iinmersed the smaller 

 tubes often in a chainformed series, giving an appearance as of an Halysites. In a 

 longitudinal section the very thick and dense walls of the coenenchymal tubes are very 

 prominent, enclosing the usual dissepiment of narrow, concave tabute. 



It is chiefly the organisation of the coenenchyma and the excessive growth of the 

 columellalike reticulation in the calicle that distinguish this species from the preceding. 



It has been found rarely in the stratum a at Norderstrand near Wisby and also 

 near the Roma myr, Gotland, in a detached specimen. 



K. Sv. Vet. Atad. Handl. Band 32. M:o 1. 



