194 BRITISH FOSSIL CORALS. 



L. aranea much resembles L. basaltiforme ; l it differs from it by its columella being 

 stouter, its septa less numerous and straighter, and its endotheca less condensed. 



4. Litiiostrotion Portlocki. Tab. XLII, figs. 1, la, lb, Ic, Id, le, If, \g. 



Astkea irregularis, Portlock, Rep. on the Geol. of Londonderry, p. 333, pi. xxiii, 

 figs. 3, 4, 1843. (Not Defrance.) 

 — — M'Coy, Syn. of the Carb. Foss. of Ireland, p. 187, 1844. 



Astrea Portlocki, Bronn, Index Palseont., p. 128, 1848. 

 Nemaphyllum clisioides, M'Coy, Ann. and Mag. of Nat. Hist., 2d series, vol. iii, p. 18, 



1849. 

 Lithostrotion Portlocki, Milne Edwards and Jules Haime, Polyp. Foss. des Terr. Palseoz., 



p. 443, 1851. 

 Nematophyllum clisioides, M'Coy, Brit. Palaeoz. Foss., p. 98, pi. iii b, fig. 2, 1851. 



Corattum astreiform. Corallites somewhat unequal in size, prismatic, and completely 

 united by their exterior walls, which are thin, but very distinct. Inner wall scarcely 

 visible in some of the calices. Septa (22 to 36), very unequally developed alternately, 

 not closely set, extremely thin, and slightly flexuous ; the principal ones extending almost 

 to the Columella, which is large, slightly compressed, and prominent. A vertical section 

 shows, that in the exterior zone of the corallites the vesicular dissepiments form 2 or 3 

 longitudinal series, and are much inclined inwardly, and that the tabula are well developed, 

 much raised in the centre, and somewhat divided exteriorly. Great diagonal of the 

 corallites 3 or 4 lines. 



Found at Bristol, Graigbenayth, Wellington, Corwen, in Derbyshire; and, according 

 to Col. Portlock, at Kildress and at Kesh, in Ireland. 



Specimens are in the collections of the Museum of Practical Geology, of Cambridge, of 

 Paris, and of M. de Verneuil. 



This species differs from L. aranea, 11 and from L. basaltiforme, 3 by the smaller size of 

 the corallites, by its septa being stouter and less numerous, and its columella being more 

 developed. It differs from L. ensifer 4 by the greater development of its walls and from 

 L. 31'Co//anum 5 by its calices being smaller, and more unequal in size, and its septa less 

 numerous. 



1 See tab. xxxviii, fig. 3. 2 See tab. xxxix, fig. 1. 3 See tab. xxxviii, fig. 3. 



1 See tab. xxxviii, fig. 2. 5 See tab. xlii, fig. 2. 



