NIAGARA GROUP. 



159 



Genus CLATHROPORA {nov. gen.). 

 [Latin, datkrum, a lattice, and pora, a pore.] 



Ramose or reticulate corals ; uniformly poriferous on both sides of the reticulate fronds, and 

 on all sides of the stems and branches of ramose forms ; apertures of cells more or less 

 quadrangular, regularly arranged in series parallel to the direction of stems, or obliquely in 

 quincunx order. 



The habit and general characters of the corals of this genus are similar to Retepora ; but 

 the two sides are poriferous, and the form and arrangement of the cells differ from those of 

 Retepoea. The branching species differs from Stictopora in being celluliferous on all sides, 

 and having the cells arranged between linear ridges or lamellae ; while in that genus the 

 branches are flattened, with non-poriferous edges, and the cells are not thus arranged between 

 laminse. From Ph^nopora, as described under the Clinton group (page 46), it differs in the 

 form of the cells, and the thickening of the stems and branches, a character which has not been 

 observed in any species of that genus. 



A more critical examination of P. ensiformis^ which likewise occurs rarely in the Niagara 

 group, shows that it differs in some respects from the other species of PniENopoRA, and is more 

 nearly allied to the following species of this genus. 



553. 1. CLATHROPORA ALCICORNIS. 



Pl. XL B. Fig. 4 a, b, c. 



Stems cylindrical below and flattened above, bifurcating and variously branched, branches 

 frequently bifurcating ; entire surface celluliferous ; apertures of cells quadrangular, rhomboidal 

 or oblong, and variable in form at the divisions of the stem ; cells consisting apparently of 

 simple tubes reaching to the axis of the stem and branches. 



This species is readily distinguished from Stictopora and Retepora, by the characters given 

 under the generic description. In its mode of branching it is very peculiar, differing from any 

 species described : the stem makes an abrupt bending at the point where each branch is given 

 off, and the branches scarcely differ in size from the stem above and below. At the point o in 

 fig. 4 a, one of the branches appear to have reunited to the stem, and a young shoot has com- 

 menced growing from the junction. This reuniting or anastomosing of the branches does not, 

 however, seem to be characteristic of the species. 



Fig. 4 c. A portion of the stipe and branches of an individual of this species, natural size. 

 Fig. 4 &. A portion enlarged, showing the oblong quadrangular apertures. 



Fig. 4 c. An enlargement of another portion of the surface, showing a difference in the form of 

 the apertures. 



Position and locality. In the shale of the group at Lockport. 



