NIAGARA OROUP. 



169 



563. 1. CERAMOPORA IMBRICATA (n. 6^.)- 



Pl. XL E. Fig. 1 a-i. 



Coral depressed hemispheric, flattened or concave on the lower side, composed of cylindrical 

 or subcylindrical tubes slightly diverging from the centre, and extending upwards in a direction 

 rectangular to the plane of the upper surface ; apertures arched or triangular, opening on all 

 sides towards the outer margin, arranged in alternating and imbricating series. 



In form and oeneral appearance, these little corals are much like some of the small Chaetetes, 

 but a slight examination of the cells suffices to distinguish them. The mass appears to be 

 composed of cylindrical tubes, which, on reaching the surface, bend abruptly outwards and 

 downwards, presenting the openings of the cells in an obliquely vertical plane facing the outer 

 margin ; giving upon the surface the appearance as of cells radiating on all sides from a centre, 

 and, unless broken through in a vertical direction, or a view of the base be obtained, it is im- 

 possible to decide otherwise. In some specimens the divergence of the tubes at the crown of 

 the specimen is very great, while in others the surface at this point scarcely differs from other 

 parts. 



Fig. 1 a, I. Upper surface of two specimens of different size. 



Fig. 1 c. Profile outline, natural size. 



Fig. 1 d. Vertical section magnified, showing structure and arrangement of the tubular cells. 



Fig. 1 e. The centre of fig. 1 a magnified, showing the upper extremities of the tubes bending 



outward, and the form of the apertures. 

 Fig. 1 /. A portion of the surface enlarged, looking into the cells, and showing the alternating 



and imbricating arrangement. 

 Fig. 1 ^. A portion of the base of a specimen, showing the circular bases of the cells. 

 Fig. 1 h. An individual of the same species, somewhat compressed, and the surface worn. 

 Fig. 1 i. An enlarged portion of the surface of 1 h. 



Position and locality. In the shale at Lockport. (Collection of Col. Jkwett.) 



564. 2. CERAMOPORA INCRUSTANS ( n. sp.). 



Pl. XL E. rig. 2 a - d. 



Coral incrusting ; surface nodulose ; cells increasing unequally from a centre or point of 

 growth, short, minute, opening obliquely outward and arranged in quincunx order. 



The specimen described covers one valve of an Atrypa ; the central or originating point of 

 growth being near the beak, from which the cells diverge in all directions, spreading more 

 extensively towards the base of the shell, and extending over the edge of the shell in the 

 other direction. The apertures are smaller, and the expanded tube or calicle on the upper side 

 shorter than in the preceding species ; the mode of grovsiih and increase are precisely the same 

 in both. 



[ Paljeontology — Vol. II.] 22 



