94 G. LINDSTRÖM, HELIOLITID^. 



and the margin is crenulated by twelve small nodules. As seen in the pl. xi, fig. 11 there 

 are in the same specimen quite regular, smooth, circular calicles along with crenulated 

 ones, the former being probably younger or more recently formed than the crenulated, 

 as is so evident in Dploepora. There are for the rest no vestiges of broader septal laminje 

 in the calicle and consequently no spines. The interiör walls of the calicinal tube have 

 only the usual fluted appearance. The tabulce are horizontal or a little wavy, more or 

 less remote. In calicles of the oldest variety the tabulae have formed a number of small 

 grooves near the wall around the septa (pl. ix, f. 4) in a certain way a sort of septal 

 grooves. On their superior surfaces, as also around the interiör side of the calicle some 

 specimens (pl. viii, f. 32 — 34, pl. ix, f. 1 — 2) bear numerous small spines, resembling the 

 acula?. They seem to be of a låter inorganic growth, consisting, as in the original specimen 

 from Borkholm of arragonite. In a specimen (pl. viii, fig. 35) the septal ends are covered 

 with druses of arragonite. 



The coenenchyma, as seen on the surface, is coarsely granular with shallow dimples 

 between the -granules. It consists entirely of convex lamella? without the least trace of 

 aculae growing on them, and this feature, as well as the total want of septal spines makes 

 it distinct from other Proporte. 



Amongst varietal forms may be cited that from Alleberg, Sweden (pl. ix, f. 9 — 10) 

 with its thick theca and closely set calicles. Probably the specimen from the stratum a 

 of Gotland (pl. ix, f. 31, 32, 35) is related to this variety, but the thick-walled calicles 

 are there moi*e closely set, in contact, and the coenenchj^ma consequently highly reduced. 



This species is chiefly a Lower Silurian fossil though also occuring in the Upper 

 Silurian of Estland and rarely in Sweden. The Swedish Lower Silurian localities are 

 Alleberg in Westergötland, Sandvik in Oland, Boda, Osmundsberg, Ostbjörka and Arfvet 

 in Dalecarlia, all belonging to the Lepttena limestone or the Brachiopod-schists. From 

 Estland I have seen specimens found at Borkholm, Pyhalep and Grossenhof in Dagö, 

 Pattakumeggi near Hapsal. From Norway I have specimens found in the islets Malmö and 

 Malmökalven in the Christiania-fiord and from Asker. In the Upper Silurian of Gotland 

 it has been found in the stratum a near Wisby, at Walve ref and Gnisvärd, in detached 

 fragments, at Klef in Sundre and Hobui-g in the stratum d. In Estland it occurs at Selja 

 pank near Taggamois in Oesel, HerkuU (ö^), Helterma {G^), Kallasto in Dagö (G^), and 

 Ruhde {H). The Upper Silurian specimens are entirely of the affinis type, as represented 

 by the Anticosti specimens from Junction Clifi'. The Museum of Stockholm also possesses 

 a specimen from the iniddle Tunguska, 22 verst above the mouth Severnaja. 



To this species also in all probality belongs a coral, which in several specimens 

 together with other fossils formed a collection belonging to the Mining Corps of Russia, 

 brought home by the Mining Engineer W. Obrutschew, geologist to the Expedition of 

 PoTANiN, in 1894, and found in the East Kwen-Lun Mountains. It is figured on plate ix, 

 figs. 5 & 6 and is derived from two localities, near the river Tsien-shui below the hamlet 

 Kaien-tze-pu and from the hamlet Tschuan-tou-pa on the same river. I owe to the kindness 

 of the Chief geologist Tschernyschev the permission to see this collection.^ 



1 The other corals in this collention were: Favosites Forbesi E. & II., Fav. aspor aff., Fav. maximus 

 QUBNST., Syringopora sp., Ptychophyllum sp. 



