io8 TABULATE CORALS. 



walls of the corallites remain quite distinct and unobliterated, 

 in spite of the thickening to which they are subjected. In 

 some instances, if the plane of the section is just below the 

 actual surface, the dense tissue surrounding the cavity of the 

 visceral chamber may exhibit small discontinuous cavities ; but 

 these are clearly merely spaces in the interior of the super- 

 ficial tubercles and ridges surrounding the opening of the 

 calices (as seen in the lower part of the section figured in 

 fig- 3 '^> PI- V.) Lastly, tangential sections show that the 

 cavities of the tubes are surrounded by short, blunt, septal 

 spines. Transverse sections taken at right angles to the axis 

 of the corallum show no features of special importance. 



Formation and Locality. — In shales belonging to the Hamil- 

 ton formation, at Canandaigua, New York. (Dr Rominger's 

 specimens are also from the Hamilton group.) 



Trachypora elegantula, Billings. 



(PI. v., figs. 4-4 ^■•) 



TracJiypora eh-gantida, Billings, Canadian Journ., new ser., vol. v. p. 254, 

 figs. 2-4. 

 „ elegantula, Nicholson, Report on the Palasontology of Ontario, 



1874- P- 59- 

 Deiidropora elegantula, Poniinger, Report on the Foss. Cor. of Michigan, 

 p. 63, PI. XXin, fig. 2. 



Spec. Char. — Corallum ramose, of slender, cylindrical stems, 

 which have generally a diameter of from one to two lines, and 

 branch dichotomously at angles of about 75°. Corallites 

 conical, nearly or quite vertical in the centre of the branches, 

 and curving gently outwards to open obliquely on the surface 

 in generally four longitudinal rows of calices, sometimes with 

 supplementary and irregularly -distributed apertures in addi- 

 tion. The central tubes of the corallites are greatly thickened 

 by the deposition of concentric layers of sclerenchyma, which 

 more or less obliterate the proper walls as distinct structures, 

 though the boundaries of contiguous tubes still remain separate. 

 The orifices of the calices are oval, their long axes parallel 



