INTRODUCTION. Ixxi 
or costal radii of the neighbouring corallites, bemg confluent, and consequently the calices 
not being definitely circumscribed. No exterior wa//s; the mterior mural investment 
well characterised. The centre of the ¢abule presenting a columellarian tubercle. 
Typ. sp., Phillipsastrea Hennahi, D’Orbigny, loc. cit.; Astrea Hennahi, Lonsdale, in Geol. Trans., 
2d series, vol. v, tab. lviii, fig. 3. 
27. Genus ERtOPHYLLUM. 
Corallum composite, and increasing by lateral gemmation. Corallites tall, cylindroid, 
and provided with a thick epitheca, which gives rise to a vertical series of short and thick 
subradiciform productions that extend to the next individual and unite them together. 
Tabule well developed, and occupying the central area circumscribed by the inner 
wall. Septal apparatus occupying the annular area situated between the outer and inner 
mural investment, but not extending into the inner or central area. 
Typ. sp., Bridophyllum seriale, nob. 
Third Tribe—LITHODENDRONIN At. 
Axis of the visceral chamber of the corallites occupied by a styliform or lamellar 
columella. 
28. Genus LITHODENDRON. 
Phillips, Geol. of Yorkshire, vol. ii, p. 200, 1835 (but not Lithodendron of Schweigger, which is not an 
admissible genus) ; Siphonodendron, M‘Coy, in Ann. and Mag. of Nat. Hist., 2d series, vol. in, 1849. 
Corallum composite, arborescent, or massive. Coraillites cylindrical or prismatic. 
Columella styliform, compact. Septa well developed, but not reaching to the columella. 
Tabule well developed. Interior wall rudimentary. 
Typ. sp., Lithodendron irregulare, Phillips, loc. cit., pl. ii, figs. 14, 15. 
29. Genus NEMATOPHYLLUM. 
Nematophyllum and Stylaxis, M‘Coy, loc. cit., 1849. 
Corallum composite, massive. Cora/lites prismatic, with a well-developed interior 
wall. Columella lamellar. Septa well developed, and united by transverse dissepi- 
ments, which extend to the columella, but do not constitute true tabule. Exterior area 
vesicular, 
Typ. sp., Nematophyllum arachnoideum, M‘Coy, loc. cit., p. 16. 
