58 G. LIND3TEÖM, HELIOLITIDiE. 



This species ranges widely from the Alpi caiTiiche iu Italy to France, Ebray, St. 

 Germain de Fouilloux in Mayenne, Belgium (Petigny), England Torquay in Devonshire, 

 Germany in many places of its western countries, especially Eifel, but also in Nassau, 

 Westphalia and the Harz mountains. 



Its geological horizon is Lower and Middle Devonian in which it is found as high 

 up as in the Stringocephalus beds. 



HelioUtes Barrandei. Penecke. 



Pl. III figs. 8—12, 17—27. 



1887. Hel. Barrandei (R. liÖKNES nomen iiudum) PeneCKE. Fauna . . . paläozoischer Korallriffe der Ostalpcn. 



Zeitschr. d. deutschen Geol. Gesellsch. Bd 39, p. 271. Taf. XX, fig. 1—3. 



1888. » » Frech. Ueber die Altersstellung des Grazer Devon. Mittheil. d. NW. Vereins Steiermark, p. 6. 



1894. » » Penecke. Das Gratzer Devon. .Jahrb. k. k. Geol. R. Anst. Bd XLIII, p. 591. 



1895. Pachycanalicula Barrandei WentzEL. Tabulaten p. 23. 



Mode of growth. This very common species has grown in large, flat or slightly 

 doineshaped disks with a thin, wrinkled epitheca on the inferior surface. 



Calieles generally small, at the highest attaining only one millimeter in diameter, 

 those from the oldest strata only 0,5 millira. Their theca does not project above the 

 surface of the corallura or only very little; it is regular and not much indented. 



Septa well developed, rather thick and short, at their interiör end they send off 

 thick, blunt spines upwards and the centre of the calicle is occupied by the tops of lower 

 situated septal spines, which sometimes cause a false appearance of a columella. The 

 longitudinal sections fig. 12, 16, show how they continue upwards and fill the central 

 space of the calicle. These numerous septal spines, issuing from the margins of the septa 

 (fig. 20), are of an irregular growth, but always tending in a bow upwards from their basis, 

 sometimes meet in the central axis of the calicinal tube, where they form an intricate 

 tissue. Some, especially the younger varieties of the Upper Silurian and the Devonian 

 ones, have a slight swelling in the apex like a little globule. 



Tabulce. These are rather scarce and much distantiated, surrounding the large 

 spines, which have grown in advance of them. They are else regularly horizontal. 



Coenenchyma- Its tubuli are upon the whole niore regularly polyedric than in the 

 former species, though in some of the varieties from the higher Upper Silurian strata and the 

 Devonian polyedric tubes are mixed with rounded or irregular ones (pl. iii, fig. 22 & 24). 

 Dr Penecke has stated that the walls in these tubuli are of great thickness. The sections 

 which Penecke has figui"ed in his above cited paper seem to me to have been derived from 

 specimens which have been subject to much pression and thence assumed their peculiar 

 oblique aspect. The calieles in these are ovale or oblique, deviating from the regular circular 

 shape in some specimens. In others again, which I owe to the liberality of Dr Penecke 

 the regularity is predominant. I have given a figure of such, pl. iii f. 24 — 25, showing 

 quite regular coenenchyma! tubuli. A longitudinal section (pl. iii f. 25) has by no means 

 thicker walls than the Swedish specimens and the thick ones seen in fig. 25 are entire 



