chief Generic Types of Palceozoic Corals. 63 



getlicr of the septa in the centre of th^ corallites to form a 

 false columella. The genus Eridophyllum, E. & H., is simi- 

 larly distinguished from the true CyathojyJiyUa^ with the addi- 

 tional character that adjacent corallites are united together by 

 epi thecal processes. In the genus Fascicularia'^ of Djbowski, 

 however, the septa are said to extend quite to the centre of the 

 visceral chamber, where they come into contact with one 

 another ; and it is ditficult to see how these can be generically 

 separated from forms like C. ca'sjn'tosum, Goldf. The genus 

 Donacophyllum of the same author appears to be hardly sepa- 

 rable from Dip)hyphyllum, the only difference which is stated 

 to exist being in the size of the vesicles of the dissepimental 

 area (Mon. der Zoanth. scleroderm. rugosa aus der Silurfor- 

 mation Esthlands &c., p. 80). 



If, on the other hand, we take the simple forms of CyatJio- 

 phyllumj we find few genera so closely related thereto as to 

 afford any great difficulty in diagnosis. From Zaphrentis 

 proper the simple Cyathophylla are at once distinguished by 

 the incompleteness of the tabulae, the presence of an exterior 

 zone of vesicular tissue, and the possession by the latter of a 

 Avell-marked fossula, formed by the folding and coalescence of 

 a certain number of the septa. 



The genus Campop)hjllum, E. & H. (PI. VI. figs. 3,4, 4 a), 

 offers, again, a transitional form between the simple CyatJio- 

 phylla and the genus Amplexus. It agrees with the former 

 in having the tabulas restricted to a central area, and in the 

 presence of an exterior zone of vesicular tissue ; whilst it ap- 

 proximates to the latter in the fact that the septa do not nearly 

 reach the centre of the visceral chamber, but leave the tabu he 

 exposed over an extensive median space. 



The genus CalojjhyUum, Dana (PI. VI. figs. 5-7 a), whether 

 valid or not, is fundamentally separated from GyatliophyUum 

 by the fact that it possesses no circumferential zone of vesicular 

 tissue, and by its complete tabulse. Whether or not Calo- 

 phyllum is distinct from Amplexus^ as denied by Edwards and 

 Haime (Pol. Foss. des Terr. Pal. p. 347), and afiirmed by 

 M'Coy (Brit. Pal. Foss. p. 91), and more recently by 

 Dybowski (Mon. der Zoanth. scler. rugosa, p. 118), can hardly 

 be settled except by a reference to the forms originally examined 

 by the great American naturalist when founding the genus. 



Our examination of the corals of the genus Htreptelasma., 

 Hall, has not yet proceeded far enough to justify us in speaking 

 positively as to its affinities. Whatever its true position may 



* This name will have to he ahandoned, having been previously applied 

 by Milne-Edwards to a well-known g-enus of Polvzoa. 



