42 BRITISH FOSSIL CORALS. 



Veretellum, for in the latter the axis is quite rudimentary. We therefore considered it 

 advisable to designate this fossil Coral by a peculiar generic name, but we are not as yet 

 sufficiently well acquainted with its characters to be able to form a complete idea of the 

 polypi to which it belonged. 



Graphularia Wetherelli is the only known species of this genus of Pennatulidse ; it 

 was discovered about twenty years ago by Mr. Wetherell in the London Clay at Hampstead 

 Heath and at Highgate. Mr. Frederic Edwards has also found fragments of it at Barton 

 and at Haverstock Hill ; and it is to his kindness that we are indebted for the specimens 

 described in this Monograph. 



Family GORGONID^E. 

 Tribe ISINtE. 



1. Genus Mopsea. 

 1. Mopsea costata. Tab. VII, figs. 3, 3<2. 



Corallum arborescent, dichotomous, and composed of epidermic basal sclerenchyma, 

 the ossification of which is intermittent, so as to constitute a series of calcified cylinders, 

 separated by non-ossified discs. The branches appear to spread out in one plane ; they 

 are thin, elongated, cylindrical, and deeply fluted longitudinally ; each of them, immediately 

 above its separation from the parent branch or stem, is bent outwards and upwards, so as 

 to represent, an inverted ogival angle. The corneous articulations, which have been de- 

 stroyed during the process of fossilization, are very thin, and do not appear to have existed 

 in any of the non-bifurcated branches. The longitudinal costse are straight, thick, pro- 

 minent, denticulated on their sides, and separated by deep furrows. All those belonging 

 to the same joint are in general of the same size ; but in some of the thickest branches, 

 where they are the most numerous (about twelve), some very small ones are sometimes 

 visible between the larger ones. The diameter of the thickest branches in the specimens 

 here described is about half a line ; that of the smallest not more than a tenth of a line. 



The genus Mopsea was established by Lamouroux, but more correctly characterised by 

 Ehrenberg, who refers to it four recent species — the Mopsea dichotoma of Lamouroux, 

 the M. gracilis, M. erythraa, and M. encrinula, Ehrenberg ; but it is doubtful whether 

 the last does in reality appertain to this division of the Isinae. Mr. Dana is of opinion 

 that the Isis corattoides of Lamarck is also a Mopsea ; but in all of these species the 

 corallum is but slightly striated, and never presents anything like the strong costae which 

 exist in the above-described fossil. 



We have seen two specimens of this Gorgonida, found in the London Clay at Holloway, 

 by Mr. Frederic Edwards. 



