Yd. 51.] RADIOLARIAN ROCKS IN THE LOWER CULM MEASURES. 645' 



calice, but less in its lower portion ; it is covered with concentric 

 rugose striae ; the calice is slightly compressed, 5 mm. in width at 

 the summit, and about the same in height. On the surface of the 

 cast there are very regular vertical lines, about 20 in number, of 

 delicate blunt spines or pustules, which would correspond to as- 

 many rows of minute holes in the actual calice, a feature which 

 has not been noticed by previous authors, but in some of the 

 specimens from the Carboniferous Limestone of Tournay, Belgium, 

 now in the British (Nat. Hist.) Museum, there are within the calice^ 

 rows of small holes instead of the usual septal striae. From near 

 the margin of the calice of our specimen the pedicel of another 

 corallite is given off, and this is nearly completely separated from 

 the parent form by a plaited septum. Our specimen is of similar 

 size to those from the Tournay Limestone, but distinctly larger 

 than that figured by Kayser from Aprath. 



Distribution. In the yellowish shales at Hannaford, associated 

 with P. Dechenianum. The only other locality in which it has 

 been found in Britain is in the Lower Carboniferous Limestone 

 series near Dunbar, whence it has been recorded by Nicholson 

 and Etheridge, Jun. On the Continent this species has been found 

 in the Culm shales of Aprath, Liebstein, and Kramberg, and in the 

 Lower Carboniferous Limestone of Tournay. 



Petraia, sp. PL XXVIII. figs. 20 & 20 a. 



Cf. Petraia (Turbinolopsis) pauciradialis , Phill., ' Pal. Foss. Cornwall, etc' 1841,. 

 p. 5, pi. i. fig. 4. 



Only the cast of the interior of the calice has been preserved ; 

 this is obliquely conical, truncate, 5 mm. in depth, 5*2 mm. wide 

 at the summit, and 4*2 mm. at the bottom. The septa are 16 in 

 number, and they have a distinct bilateral arrangement. A cardinal 

 septum reaches nearly to the centre of the base of the calice, and 

 there is a small depression at its free end. It has on each side a 

 group of three septa. The alar septa connect with a low ridge 

 which curves round the small central depression, and connected 

 with this is the counterseptum and three other septa on each side 

 of it. The septa appear to be narrow, with smooth, free margins. 

 On both sides of each septum there is a row of minute holes — shown 

 in the cast as small pustules — which are probably connected with 

 the insertion of the mesenteric muscles. 



In P. pauciradialis, Phill., there is a greater number of septa,, 

 and their margins are said to be denticulate. 



From Hannaford Quarry, near Barnstaple. 



(c) Crinoids. 



Casts of detached joints of crinoidal stems, similar to those which 

 Phillips provisionally named Cyathocrinus distans (' Pal. Foss.' 1841 , 

 p. 135, pi. lviii. fig. 49*), are fairly numerous in the same beds with 

 the other fossils, but there is nothing in them to distinguish the» 

 particular genus to which they might belong. 



Q. J. G. S. No. 204. 2 z 



