NIAGAKA GROUP. 



157 



The following species (including Plate xl b in part, and all of Plates xl c, d, e & f), 

 probably belong to the Bryozoa group ; though it is not possible, in the present state of our 

 knowledge, to decide positively in regard to some of them. The Ceramopora, in its depressed 

 hemispheric forms, has a very close resemblance to the true corals ; while in the expanded in- 

 crusting forms, they seem unequivocally of the Bryozoa type. The other genera have not, 

 either in the form of cells or mode of growth, the character of true corals. 



551. 9. STICTOPORA PUNCTIPORA (n. sp.). 



Pl. XL B. Fig. 2 a, b, c. 



Axis flattened, bifurcating ; edges striated ; surface marked by minute rounded (sometimes 

 scarcely oval) or punctiform cells ; border of the cells more elevated on the upper side ; cells 

 arranged in ascending rows, having about fourteen in each row and ten in the width of the 

 stipe. 



This species is remarkable for the minute rounded apertures of the cells, differing in this 

 respect from all the species described ; a single species only, in the Chazy limestone, ap- 

 proaches to this one in the form of the cell apertures, while it differs very essentially in all 

 other respects. The present species, though not abundant, is common in the calcareous layers 

 in the shale of the Niagara group. The form of the apertures is so nearly like those of Trenia- 

 topora ostiolata, that the surface may be mistaken for that coral, and it often requires careful 

 attention to discriminate between the two. In the Stictopora, however, the apertures are more 

 nearly round, and in a small degree more closely arranged, and may be followed in oblique 

 ascending lines across the stipe. Where the edges of the stipe are visible, there is no difficulty 

 in distinguishing between the genera and species, even where specimens of Trematopora are 

 flattened as they sometimes are. 



A single fragment of this species presents a peculiar feature, as shown in fig. 2 c. The sub- 

 stance of the flattened stipe rises in two rounded elevations, which become cylindrical and 

 celluliferous on all sides, the apertures in the flattened stipe continuing into and along the ^des 

 of the cylindrical stem without any diversion or interruption. These bases of cylindrical stems 

 present a close approximation to those of Trematopora, and the phenomenon is very re- 

 markable, inasmuch as the structure of the latter genus differs in a considerable degree from 

 Stictopora. 



Fig. 2 a. A fragment of a bifurcating stipe of this species, natural size. 



Fig. 2 b. A portion of the surface enlarged, showing form and arrangement of cells. 



Fig. 2 c. An enlargement of the fragment referred to above, showing the bases of two cylin- 

 drical stems connected with the flattened stipe, and the rows of cells continuous from 

 one to the other. 



Position and locality. Upon the surface of calcareous layers in the Niagara shale at Lock- 

 port. 



