52 GUIDE TO THE FOSSIL INVERTEBEATE ANIMALS. 



Table^^"^' ^^^^^^^^^^^^s species (Table-case 5). Here the tubes are 

 ^ 8."^^^^ separate, but connected by cross-canals, and the tabulae are 

 funnel-shaped (Fig. 22, h). The living alcyonarian, Clavu- 

 laria, has a tubular skeleton with similar cross-canals, and 

 the organ-pipe coral, TuMpora, has tabulae either flat or 

 funnel-shaped and cross-canals running in the flat expansions 

 that connect the tubes ; therefore many place SyringoiJora 

 and the Favositidae with these Alcyonaria. In all these 

 genera the tubes of eacli colony are of equal size, and doubt- 

 less contained equally developed polyps. On the other side 

 of this Case is Heliolites (sun-stone), in which the surface 

 shows openings like little suns surrounded by smaller circular 

 openings ; in section the colony is seen to be formed of 

 tabulate tubes of two sizes. Heliolites and its allies are 

 explained by reference to Heliopora (see Table-case 1), a 

 living Alcyonarian, in which the larger tubes contain com- 

 plete polyps, and the smaller ones contain simple sacs of 

 the common flesh of the colony. Halysites, the chain-coral 

 (Fig. 21 a, h), consists of tabulate tubes, flattened, and joined 



h c 



Fig. 21. — Silurian Anthozoa, possibly Alcyonaria, from the Wenlock Lime- 

 stone of Dudley, a, Halysites catenularius, natural size ; h, some of 

 its tubes seen in section, to show the tabulae, slightly enlarged ; c, Aulo- 

 jjora, growing on a shell, enlarged | diameter. (From specimen K 2067, 

 Table-case 8.) 



by their edges, with no connecting pores ; in some species 

 all tubes are of equal size, in others some tubes are much 

 smaller ; it is probably an Alcyonarian. Aulopora, apparently 

 an ally, grows in a low network over shells and corals 

 (Fig. 21 c). A slab of Silurian limestone from Gotland, 

 between Wall-cases 5 and 6, is largely composed of Favosites 

 and Halysites. 



Table-case In the next Case are Silurian Zoantharia Eugosa or 

 7- Tetracoralla. Here come the conical Omphyma with root- 

 like supports (Fig. 22 a), the broadly spreading cups of 



