82 G. LINDSTRÖM, HELIOLITID^. 



The septa are not lainellar, they consist of a dense row of large, closely packed 

 spiiies (fig. 18), which reach to the centre and nearly obscure the thin, much distantiated 

 tabulte. The granulated septa, as seen in the bottom of the superficial calicles, f. 16, represent 

 the bases of the spines, which latev grow out from these. In a section from the older 

 portions of a polypary (fig. 11) there are also small aculaj on the superior surface of the 

 tabulas, no septal spines in the lowest parts and rather scarce in the beginning. But 

 there is no telling whether this is the original structure or rather a condition due to 

 inorganic changes during the fossilization. 



The aureola is distinct and regular in the typical speciraens (as fig. 6). Owing to 

 the proximity of the calicles there is not much space left foi' other coenenchymal tubes. 

 The coenenchyma in a longitudinal section is chiefiy vesicular, the convex lamellfe of 

 greatly different size. There are longitudinal rows of acula; which also combine into 

 rods and constitute irregular tubuli (tig. 18) enclosing traverses. 



There are indications of coenenchymal gemmation (fig. 10), as well as of a calicinal 

 one, in small colonies rising out from the surface of older calicles. 



This species has been frequently found in the older strata of Gotland. It does not 

 occur deeper than in the marly beds of h and not higher than in the Wenlock limestone 

 {cl) of Gotland. It has been found in the following localities. Ryssnäs in Fårö, Hall, 

 Halls huk, FoUingbo, Dalhem, Wisby {b, c & cl), Walveref, Blåhäll in Tofta, Nyrefs udde 

 in Tofta, Gnisvärd, Westergarn, on the shore south of Westergarn, Eskelhem, Eksta, Lilla 

 Carlsö, Stora Carlsö, Hoburg. 



Out of Gotland it is said also to occur in the Upper Silurian of England, from 

 where I have not seen specimens. 



Specimens sent to me from thé late Prof. James Hall of Albany, under the deno- 

 mination Heliolites spinipora from Lockport, N. York seems to belong to this species, not 

 to Propora as M. Edw. & Haimk, H. N. Cor. III, p. 242 have stated. 



FUismopora follis. Euw. & H. 

 Pl. VII, ligs. 19—20. 



1850. Pliisiriopora follis EdW. & H. Pol. paheoz., p. 223, pl. 16, ligs. 3, 3a. 



1860. » » Ferd. Hoemer. Tennessee, p. 24, TaF. II, tigs. 6, 6«. 



1860. » » Edw. & H. H. Nat. Cor., Ill, p. 240. 



1876. » » ROMINGER. Michigan, p. 14, pl. III, lig. 2. 



1879. » » QUENSTEDT. Petref. Dentschl., p. 147, pl. 140, lig. Irt — c^. 



1883. >. ■!> Ferd. Koemer. Letha;a Gcogn., p. 511. 



1885. » ^ Davis. Kentucky Fossil Cor., pl. I, Hg. 9 (f. 10 tou indistinet.). 



It grows as a rounded, irregularly spherical coralluiu.' 



The calicles are circular not at all exsert, not much more than one millim. in 

 diameter. 



^ The specific uamc has been dcrived from tho latin fullis, signifyiiig a pouch or a rouudcd säck. 



