THE ANTHOZOA PERFOHATA OF GOTLAND. 



ged in four cycles, but it is very difficult to make ont their order or to discern the 

 different cycles. Nevertheless the peculiar arrangement of the septa of a younger order 

 tending to coalesce with those of an older is clearly seen. The septa are incompletely 

 united between themselves by synapticulas or a kind of very imperfect dissepiments, so 

 highly different from the true dissepiments of the rugosa. They are formed by slender 

 and curved points, and branches which t;ike their origin on the lateral surfaces of the 

 septa. The septa rise above and beyond the rim of the calice, and are on their interiör 

 free edge regularly lacerated or denticulated, and their lamina is perforated like a network. 

 In the grooves of the calicnlar expansions septa Were formed in direct continuation to 

 •those on the inside of the calice. The exteriör edges of the septa are by no tneans an 

 independant structure deserving to be designated by a term of their own (»costse»), and 

 continue uninterruptedly from below upwards. They are so closely set at the periphery 

 of the coral as to leave no place for the formation of any interseptal structure deserving 

 the naine of wall. Indeed I have in no instance in this coral met with anything at all 

 resembling an independant wall. ToAvarcls the central axis of the coral or the calice the 

 septa become, as it were, dissolved in a confused mäss of spongious texture entirely com- 

 posed of spiny and branching trabeculas, thereby forming a large and very beautiful co- 

 lumella rising in the shape of a low, semiglobular cone in the -shallow bottom of the 

 calice. It occupies about two thirds of the surface of the calice. 



In a transverse section of the coral two different strata may be distinctly discerned, 

 the exteriör of radiating elements composed of the septa and enclosing the inore 

 irregular central stratum consisting of the columellar tissue. These strata are not quite 

 as ^ TT ell discernible in a longitudinal section, where the wavy lines of the successive 

 growth follow each other, somewhat elevated in the middle and sunk fonvards the edges, 

 again to be elevated at the rims of the calice. 



Although possessing some Palasozoic features, as the calicular expansions and the 

 gradual diminution of width, this coral shoAvs its very close affinity to the Recent perfo- 

 rata in the structure of its septa and columella, in the formation of its epitheca, and its 

 mode of reproduction. Amongst these corals this Palreozoic one may at once be placed 

 in the division of the Eupsammida? of Milne-Edwards and Haime. It possesses the 

 mode of reproduction of the genus Dendrophyllia and of Coenopsammia, the geinmae 

 budding forth from the sidewalls of the parent coral in the same Avay, it has the epi- 

 theca of Balanophyllia and septa of four incomplete cycles as Endopsainmia and a spon- 

 gious columella resembling that of the last mentioned genus. It thence seems to unite in 

 itself many of the characteristics of genera, Avhich have succeeded it in much låter times, 

 and to be in fact one of those types, Avhich have been so aptly called »forerunners». 



Ouf knowledge of the geological history of the Eupsammidse is very fragmentary, 

 and a great break intervenes between this Upper Silurian Calostylis denticulata and its next 

 congeners, Balanophyllia Gravesi Mich. and the Stephanophyllia? of the LoAver Chalk, 

 these being the first knoAvn successors to Calostylis. 



Calostylis denticulata is found abundantly in the beds of shale and limestone at 

 Wisby, Isle of Gotland, and it ranges över an extent of three Swedish miles (above eighteen 

 english) along the shore of the Baltic. It is also, as above stated, found in Nonvay in the 



