14 



species from the Corniferous Limestone of Ontario. One of these, viz., S. concentrica (Gold.), 

 is a well known European species ; but, owing to its mode of occurrence and state of preserva- 

 tion, I regard its identification as, to say the least of it, doubtful. The other four species are 

 new. 



2. STROMATOPORA TUBERCULATA (Nicholson). 



(Plate I., figs. 2 and 3.) 



Sframatopora tuberculata. Nicholson. Annals and Magazine of Natural History, August, 

 1873. Plate IV., figs. 2 and 3. 



Fossil forming crusts or irregular expansions of varying thickness, and often covering 

 large surfaces, composed of numerous concentric calcareous laminae, separated by delicate 

 calcareous rods, pillars, or dissepiments, which are disposed at right angles to the laminae and 

 mark off minute cellular compartments or interspaces. The laminae and intervening spaces 

 are about five in the space of one line, sometimes four ;. and the vertical pillars or dissepi- 

 ments are comparatively strong and placed at proportionately remote intervals. The 

 upper surface of the mass is more or less strongly undulated, and is covered with close- 

 set, conical, clavate or fungiform tubercles, the elevation of which is about from one- fiftieth 

 to one- twenty -fifth of an inch above the general surface. The tubercles would seem to be 

 sometimes perforated, but are more commonly imperforate, and they are placed in irregular 

 sinuous lines, three or four sometimes coalescing longitudinally. They are separated from 

 one another by about their own width (more or less), about one-twenty-fifth of an inch. When 

 the fossil is broken, it is seen that similar tuberculated surfaces occur at various depths in 

 the mass, concentric with one another, and separated by laminated and reticulated tissue. 



The under surface iscovered with a thin calcareous basement-layer, which is thrown into 

 very numerous, concentrically-arranged, undulating wrinkles. This surface is not unlike the 

 epitheca of a Favosites, but is not so smooth, and does not appear to have been absolutely 

 unbroken. 



Both upon the upper surface and the lower are placed at irregular intervals rounded 

 apertures from half to two-thirds of a line in diameter. They appear to be wanting in some 

 specimens, which, however, are fragmentary ; whilst they can be readily detected in others. 

 They are the openings of canals which penetrate the mass in a more or less vertical direction, 

 and they can hardly correspond with anything except the oscula of sponges. The distance of 

 these apertures apart varies from two lines to half an inch. 



As regards one of the most important points in the structure of S. tuberculata, namely 

 the large canals and exhalant orifices, I have now obtained fine specimens which set the 1 " 

 question at rest. In my original description (Loc. tit. p. 93), I stated the case as follows : 

 " Many examples exhibit rounded openings or tubes, from half a line to a line in diameter, 

 descending at right angles to the mass, and placed at varying intervals. These openings 

 are not elevated above the general surface. They are not constant in their occurrence, though 

 very generally present; and I have not been able to satisfy myself that they are not truly ex- 

 traneous to the fossil. They may, perhaps, be annelidous in their nature ; or they may be 

 due to the fact that the organism has enveloped a colony of Syringopora, which has subse- 

 quently been dissolved away." The specimens now in my possession, however, prove conclu- 

 sively that these canals and apertures are truly parts of the fossil, and they appear to be 

 strictly comparable to the oscula of sponges. They are mostly to be detected upon the upper 

 surface, but in one large specimen which seems to have grown from a broad base of attach- 

 ment, and then to have spread out laterally in an irregularly cup-shaped form, they are plen- 

 tifully developed on the lower surface. There is thus every reason for concluding that S. 

 tuberculata is truly a calcareous sponge ; and the chief question remaining is, whether it can 

 with propriety be retained in the genus Stromatopora. My own opinion is against forming a 

 new gonus for its reception, since it has the essential structure of Stromatopora, and the diffi- 

 culty which I experienced at first in detecting the oscula in examining even a large series of 

 specimens, has convinced me that the occurrence of similar openings may well have been over- 

 looked even in the type- species of this genus. 



Stomatopora tuberculata is readily distinguished by its very coarse reticulation, the tuber- 

 culated nature of the upper surface, the concentrically-wrinkled under-side, and the presence 

 of remote and irregularly placed oscula, which are not situated upon eminences. Whether the 



