202 BRITISH FOSSIL CORALS. 
“Tubes averaging 6 lines in diameter, mostly hexagonal; external surface coarsely 
striated longitudinally, and transversely marked with strong curved irregularities of 
growth, the convexity of the curves upwards; horizontal section, 63 slender radiating 
lamellee, converging from the walls towards the flat central style or axis, which is about 
one line in width; one half of the lamelle reach the centre, the mtervening ones reach 
rather more than half way; outer area exhibiting numerous transverse vesicular plates 
between the radiating lamellee. 
“Vertical section, axis straight, riband-like, inner area broad, of slightly-curved 
vesicular plates, forming rows of lengthened irregular cells, extending obliquely down- 
wards and outwards from the axis, about three in a row ; ozfer area of rows of small, hemi- 
spherically-curved plates, including small, rounded cells, extending very obliquely up- 
wards and outwards, about 5 or 6 in each row. 
“From the carboniferous limestone of Derbyshire.” (M‘Coy, op. c7t.) 
16. LirHosrrori0oN ARACHNOIDRUM. 
NEMAPHYLLUM ARACHNOIDEUM, M‘Coy, Ann. and Mag. of Nat. Hist., 2d series, vol. ili, 
; p. 15, figs. a, B, and p. 16, 1849. 
SryLaxis aracuNorpEA, Milne Edwards and Jules Haime, Pol. Foss. des Terr. Paleoz., 
p. 454, 1851. 
NEMATOPHYLLUM ARACHNOIDEUM, M‘Coy, Brit. Paleeoz. Foss., p. 97, pl. iii a, fig. 6, 1851. 
“ Stars, with from four to seven angles, and averaging from 6 to 9 lines in diameter ; 
aais very thin, 1 line wide; vertical section, ner vesicular area wider than the outer of 
little arched plates, inclining slightly downwards from the axis; it takes about two (rarely 
one) of those plates to reach from the axis to the extent of this area, or two irregularly 
elongate, unequal cells in a slightly oblique line, from the axis to the wall of the inner 
area; outer area separated from the inner by a sharp, distinct le on each side, and 
composed of much smaller and more highly curved vesicular plates, so that there are from 
5 to 7 small, nearly equal, rounded cells, extending in a line obliquely upwards and out- 
wards, from the inner area to the outer walls of the tube; horizontal section, boundary or 
divisional walls thin, stars radiated with from 50 to 55 very thin lamella, of equal thick- 
ness, but alternately long and short, the long reaching to the centre, the short barely 
entering the edge of the inner area; weathered surface, stars flattened, separated by a 
depressed line; canver area forming a gentle convex, oval, or circular boss, with the axis 
forining a short impressed line in the middle; the radiating lamelle exhibit numerous 
delicate, curved, interstitial plates in the outer area, but none in the inner area. 
“Forms large masses in the carboniferous limestone of Derbyshire.” (M‘Coy, op. cit.) 
