imperfectly-known Species of Sti-omatoporoids. 21 



this specimen, which is only a fragment, the coenosteum 

 would appear to have been at least 4 inches wide and about 

 I inch thick in the centre. 



Formation and Locality, Wenlock Limestone, Wisby, Got*^ 

 land {coll. Dr. George J. Hinde) . 



Rosenella pachyphylla^ Nich. (PL I. figs. 6 and 7.) 



Coenosteum apparently massive, composed of undulated 

 laminee, which unite to form a tissue of elongated vesicles of 

 very varying sizes, the larger ones being from 5 to 15 millim. 

 or more in length. The upper surfaces of the laminai are 

 covered with exceedingly minute miliary granules or 

 tubercles. The laminae vary much in thickness, many of them 

 being from | to 1 millim. thick. The thicker laminae have 

 a peculiar tubulated structure, being traversed by minute 

 irregular canals, which penetrate them vertically, and thus 

 place successive vesicles in communication. These tubuli are 

 seen in vertical sections (PI. I. fig. 6) crossing the laminae at 

 right angles. In tangential sections (PI. L fig. 7) the tubuli 

 are seen in places where the section happens to correspond 

 with one of the laminte in question as close-set rounded per- 

 forations in the substance of the lamina. These tubuli pro- 

 bably served to convey stolons of the coenosarc, and, in the 

 last layer of vesicles, for the lodgment of zooids. 



Ohs. The only specimen I have seen of this species is a 

 fragment of a larger mass, and has a thickness of about 2 

 inches, indicating that the coenosteum grew to a large size. 

 Unfortunately neither the under nor the upper surface is 

 satisfactorily preserved. The general structure of the skele- 

 ton conforms to that of Rosenella dentata, Rosen, and U. 

 macrocystis, Nich. ; but the present species is sufficiently 

 separated from these by the exceedingly minute size of the 

 tubercles covering the upper surface of the larainas, and still 

 more by the peculiar thickening and tubulation of many of 

 the laminge. 



Formation and Locality. Silurian (" Zone of Pentamerus 

 esthonus "), Kattentack, Esthonia. 



EXPLANATION OF THE PLATES. 

 Plate I. 



Fi(/. 1. A specimen of Stromatoporella curiosa, Barg., sp., of the natural 

 size, forming a crust upon a Rugose coral. Middle Devonian, 

 Biicliel (Pafeath district). 



Fig. 2. Tangential section of the same, enlarged twelve times. 



