360 Prof. A. E. Verrill on the Affinities of Palceozoic 



The animals of Pocillopora are exsert in expansion, with a re- 

 gular circle of 12, nearly equal, stout, tapering tentacles sur- 

 rounding the circular disk* ; and 12 internal, radiating, fleshy 

 lamellae show through the disk. Thus they closely resemble 

 the polyps of Stylojjhoray Porites^ and Madrepora^ which are 

 among the most typical of true polyps. The existence of 

 stellate cells, with 6 or even 12 well-developed radiating septa, 

 in several species of Pocillopora (e. g. P. elongata, Dana, P. 

 plicata^ D., P. stellata, V.) should be sufficient evidence that 

 such corals have no Acalephian affinities whatever, even with- 

 out the conclusive evidence derived from a study of the living 

 polyps. 



The Silurian genus Columnaria appears to belong to a dif- 

 ferent family ; and if not actually a member of the Astrceidce, 

 it should at least be referred to a family very near that group. 

 It has from 24 to 36 well-developed, imperforate, radiating 

 septa, those of the first cycles wider and, in C. stellata (Hall, 

 sp.) , reaching the centre, while those of the last cycle are quite 

 narrow. The larger septa have the upper edge finely serrate. 

 The walls of the adjacent cells are united together as in 

 Goelastrcea and Goniastrcea ; they are solid and apparently 

 imperforate. The genus closely resembles Goelastrcea ; but the 

 budding is marginal or interstitial, while in the latter the cells 

 divide across the middle. 



Another well-known and important group of tabulate corals 

 was abundantly represented in the Paleeozoic seas by the genus 

 Favosites^ with its numerous species, and by several other 

 allied genera, constituting the &\xbidcm\\j Favositince of Edwards 

 and H aime. In these corals the walls are thin and perforated 

 by more or less numerous pores or foramina, which are small 

 in Favosites, but large and numerous in Koninckia. The cells 

 are usually crowded and polygonal ; and there is no coenen- 

 chyma. The radiating septa are sometimes obsolete, but 

 usually 12 or 24, which may be continuous or represented 

 only by vertical rows of spine-like points, as in Favosites and 

 the existing genus Alveojyora (fig. 1, b). The transverse 

 septa are variously developed, being often nearly flat but with 

 the intervening spaces variable (as in Favosites), sometimes 

 partly vesicular and incomplete (as in Emmonsia), not unfre- 

 quently convex and vesicular (as in Miclielinia) , rarely infun- 

 dibuliform (as in Roemeria) . It is obvious that this group has 

 no relationship with the MillejporidcBj and at best only a distant 



* Trans. Conn. Academy, vol. i. p. 523 (Pocillopora lacera, V.). The 

 polyps of P. damicornis, as Ugared by Quoy and Gainiard in the ' Voyage 

 of the Astrolabe,' are quite similar. 



