chief Generic Types of Palicozoic Corals. G7 



When we consider the above-mentioned characters as dis- 

 played by longitudinal and transverse sections of this coral 

 (PL VI. %s. 1-1 1), we are led to the conclusion that it is 

 fundamentally distinguished from all the forms of Zaphrentis 

 proper (1) by the fact that the tabulas do not extend com- 

 pletely across the visceral chamber, (2) by its possession of an 

 exterior vesicular zone, formed by very numerous dissepiments 

 filling the interseptal loculi, and (3) by the fact that the septal 

 fossula is not formed by the bending round and coalescence of 

 a certain number of the septa, but is constituted by a funnel- 

 shaped depression of each successive tabula (whence the name 

 of Siphonophyllia applied by Scouler to forms presenting this 

 peculiarity) . 



On the other hand, it agrees with the genus Cyathophyllum^ 

 &S, we have defined it, (1) in the fact that the tabulae are re-, 

 strlcted to a central area, and (2) in the possession of a well- 

 marked circumferential zone of lenticular cells, which are ar- 

 ranged in layers inclined upwards and outwards. In the pos-, 

 session of a well-marked fossula, on the contrary, it certainly 

 differs from the more typical simple Cyatliopliylla^ though some 

 of these do actually possess a small or rudimentary fossette. 

 A more serious difference, howxver, is found in the fact that 

 the septa do not appear to reach the centre of the visceral 

 chamber, but fall short of this point, and leave the tabular 

 exposed. This, at any rate, is what is shown by transverse 

 sections (PI. VI. figs. 1 b-1 i), though, according to Edwards 

 and Haime, the septa are continued in the form of striaj nearly 

 to the centre of the highest of the tabulte *. 



So far as the evidence in our possession goes, w'e have no 

 doubt as to the propriety of removing Z. cylindrica from the 

 genus Zaphrentis ; and we are inclined to think that it should 

 be placed in Cyathophyllum^ in spite of the minor differences 

 above noted. In that case the original specific name will have 

 to be restored, and it will stand as CyathophyUum giganteum^ 

 Mich. If the above-mentioned differences should be consi- 

 dered of sufficient weight to separate it generically from Cya- 

 fhojihyllum, then the genus Caninia will have to be resuscitated 

 for its reception, and it will revert to its original title of Caninia 

 gigantea, Mich. 



The genus CyathophyUum has a wide range in time, ex- 



* Mucli stress cannot perhaps be laid upon the fact that the septa fall 

 short of the ceuti-e. It is true that in the most typical Cyathophylla they 

 extend to the centre of the visceral chamber ; but there is at least one 

 marked exception to this rule, \iz. C. parackia, M'Coy (PI. YII. figs. 7 b, 

 7 c), in -which the septa fall short of the centre, and leave the tabulae ex- 

 posed to view in the centre. 



