114 PKOF. P. M. DUNCAI^ ON THE STKUCIUEE AND 



of observing that I regard some of the so-called Astrocoenice from 

 the South-Wales Lias as clearly referable to another genus." No 

 reason was given and no argument was brought forward in order 

 to substantiate this statement. 



In the communication now under consideration (p. 369) the 

 author, ignoring the morphological arguments brought forward by 

 me * to explain the placing of the Infra-Lias forms in the genus 

 Astrocoenia, wrote as follows : — 



" Genus Stylastejea, E. de From. 



" This genus was created in 1860 by M, de Fromentel for the 

 reception of two species of composite corals from the Amm.-angu- 

 latiis beds of the Lias of the Cote-d'Or. It is characterized by 

 circular calices, ivTiich are not united hy their walls f, but by ccenen- 

 chyma, having costse which are non-confluent and denticulated, by 

 septa which are exsert and strongly denticulated, aind by a well- 

 developed and styliform columella. That some, if not all, of the 

 so-called Astrocoenice from the Sutton-Stone and Brocastle deposits 

 in South Wales are referable to this genus, whatever may be its 

 affinities, I do not entertain the least doubt." 



The affinities cannot be omitted, however, from the argument, 

 and, moreover, the above diagnosis is incomplete. 



It does not give the whole of the facts, and they will be found in 

 De Fromentel's ' Introduction a I'etude des Polypiers Fossiles,' 1861, 

 p. 223 : — " Ce genre correspond exactement aux Stylines et n'en 

 diifere que par ses cloisons dentees." He gives the following posi- 

 tive diagnosis : — " Corallum of a rounded form. The calices pro- 

 ject, are circular, and united by the great development of the 

 costae. The costse are broad, and pass to meet, but not to become 

 confluent with, those of the neighbouring corallites. The septa are 

 regularly and strongly dentated ; the columella is styliform and 

 well developed. The walls are not hidden by the septo-costal rays. 

 The gemmation is between the calices." The species were first 

 of all described by De Fromentel in Martin's ' Infra-Lias de la Cote 

 d'Or,' p. 94, pi. viii. ; the position of the gemmation is indicated, 

 and it is clear that the walls of the corallites are united by more 

 or less cellular exotheca, constituting a coenenchyma, as in Stylina. 



The species of Stylastrcea have projecting circular calices, a 

 great development of the costse, thin walls united by a coenenchyma, 

 and extra- calicular gemmation. The arrangement of the septa is 

 in definite cycles. 



The Stylastrseans are nothing more than Stylinae with dentated 

 septa, and the South-Wales corals which were placed in the genus 

 Astrocoenia are genericaUy distinct from them. 



This may be understood from what has already been stated above, 

 and the proofs are also to be found in a communication "On the 

 Astrocoenise of the Sutton-Stone and Equivalent Deposits of the 

 Infra-Lias of South Wales," which precedes this reply. In that essay 



* Op. cit pp. 24-26. t The italics are inserted by the author of this reply. 



