17 



Genus Coscinocyathus. 



Associated with Ethmophyllurri Hindei, at least one locality,, 

 are other fossils, usually more or less fragmentary, which possess, 

 in addition to the structure common to both ArchcEocyathus and 

 Ethmojjhyllumj the distinguishing features of Coscinocyathus, 

 Bornemann."^ This genus, according to Dr. Hinde, contains 

 " turbinate, open saucer-shaped, or subcylindrical forms, resem- 

 bling Archceocyathus in the character of the outer and inner wall- 

 plates, and of the septa, but possessing in addition transverse 

 cribriform plates, which subdivide the vertical interseptal loculi. 

 These transverse plates, which may be compared to the tabulae in 

 fossil corals, only that they are perforate, extend quite across 

 the space between the outer and inner laminae of the wall, but 

 they do not extend into the interior hollow cup. In some cases 

 they are nearly horizontal, in others they are arched, or even 

 oblique." 



And here I may remark on the extraordinarily resemblance 

 which exists between the lithological features of the Sardinian 

 rock, with the appearance of its fossils when seen in section, and 

 the Wirrialpa and Ardrossan limestones, so much so as almost 

 to make one boldly assert that the limestones are identical. 



The fossils, now referred to Coscinocyathus, are of larger size 

 than the preceding, Ethmojyhyllum, with a greatly increased 

 number of septa, usually in the form of portions of the septal 

 area, straight or curved, or more or less irregularly shaped coral- 

 lums, sometimes oval or oblong, similar to Bornemann's C. cancel- 

 latusl;j or, at other times, semi-meandering masses, but the out- 

 line, as now seen, always more or less dependent on the angle at 

 which the limestone is cut or fractured (PI. III., fig. 1). 



In a frag-ment of a large septal, area (PL III., fig. 7) tissue is 

 visible between the septa, in every way answering to Dr. Hinde's 

 description, and Bornemann's figures of Coscinocyathus dianthusl 

 and C. anthemis.% This specimen, which seems to conclusively 

 prove the presence of this genus, is from Wirrialpa. In another 

 specimen, which from the number of the septa, and their size, 

 would also appear to be part of a Coscinocyathus, the outer wall 

 plate (PL III., figs. 5 and 6) with its perforations is plainly 

 visible. The pores are arranged in vertical alternating rows, from 

 three to four between every two septa, and give rise to a 

 roughly quincuncial arrangement. It also shows the increase 

 in the number of septa by the interpolation of new ones. [n 



*DieVerst. Cambrischen Schichtensystems der Insel Sardinien, 1886. 

 p. 59. 



+ Zoc. ciV., t. 20, f. 2. 

 Xlhid, t. 17, f. 6 and 7. 

 %Rid, t. 21, f. 2. 



