CORALS FROM THE CORAL RAG. 103 



Comoseris meandnnoides} which we know only by M. Michehn's figures, appears to 

 difier from the British fossil here described, by the serpentine form of the ridges, which 

 pass without interruption from one edge to the other, and by the septa being more unequal. 

 In Comoseris vermicularii the lidges are thinner, the septa much more delicate and closer 

 set. 



Gemis Protoseris.^ 



Protoseris Waltoni. Tab. XX, figs. 1, \a, \h, \c. 



Corallum composite, foliaceous, subcrateriform, sometimes lobate and invaginated. 

 The outer surface is formed by a common basal plate covered with delicate, granulated 

 costal striae, which are well marked, and project somewhat unequally alternately; they are 

 almost straight, and extend from the central basal point to the edge of the corallum, but 

 dichotomise sometimes. This basal plate presents also some transverse constrictions and 

 tumefactions, which form ill-defined accretion ridges, but are not strongly characterised. 

 The upper (or inner) surface of the corallum is almost smooth, and presents neither valleys 

 nor ridges, nor cristse, but is covered with shallow calices irregularly disposed. These calices 

 are individualised by the existence of a well characterised but shallow central depression or 

 fossula, but are not distinct at their circumference where they are completely blended 

 together, the septa passing, without any interruption, from one visceral chamber to another 

 (figs. \a and \b). In the centre of each fossula there exists a small papillose columella, 

 formed by the inner septal denticulations. There are from thirty to forty septa round each 

 calice, but not more than half of these extend to the fossula; they are small, delicate 

 laminse, with a crenulate edge, and are all nearly equal in thickness ; some are straight, 

 others more or less bent, or even flexuous, and many of them become cemented to one of 

 the adjoining ones at their end, so as to assume the appearance of bifurcation. 



We have seen but one specimen of this remarkable fossil ; it was found in the Coral 

 Rag at Osmington, near Weymouth, by Mr. Walton, and communicated to us by that 

 active palaeontologist. 



This coral cannot be referred to any of the generical divisions established in the intro- 

 duction to this Monograph, but must form the type of a new genus to which we have 

 given the name of Protoseris. This genus is closely allied to Agaricia^ Leptoseris^ 

 Cyatlioseris^ Oroseris] and Comoseris,^ but differs from all by its frondescent lamellar 



' Pat'onia meandrinoides, Michelin, loc. cit. ; Comoseris meandrinoides, D'Orbigny, Prodr., vol. ii, p. 40. 



2 Tab. xxiv, fig. 1. 



3 See our Memoire sur les Polyp. Palseoz., etc., loc. cit., p. 129. 



■* Introduction, page xlix. ' lb., p. xLx. ^ lb., p. xHx. 



7 Milne Edwards and J. Haime, Polyp. Palseoz., etc., p. 131. ^ See p. 131. 



