CORALS AND BRYOZOA. 197 



This species may be distinguished from L. stellata by the absence of promi- 

 nent monticules, the nearly equally elevated peristomes, and the coarser and 

 more irregularly disposed vesicles: from L. vesiculata by the more distant, 

 more elongate, less distinctly trilobate cell apertures, and the circular, not 

 depressed, maculae ; the maculae of that species being elongate and depressed : 

 from Fistulipora trifaria by the much less distinctly trilobate cell apertures and 

 the absence of mesopores : from L. substellata, of the Upper Helderberg group, 

 by the more elongate, more distant cell apertures, the usually more equally ele- 

 vated peristomes, and the much less prominent maculae : from L. ramosa by the 

 incrusting mode of growth, elongate cell apertures, and smooth inter-apertural 

 space : from L. cuUellata, L. colliculata, and L. cornuta it may be easily distin- 

 guished by the absence of monticules. 



Formation and locality. Hamilton group. West Williams, Ontario. 



LiCHENALIA DISTANS, n. Sp. 



NOT PIQUBBD. 



ZoARiUM consisting of explanate fronds incrusting other objects, usually Cyatho- 

 phylloid corals ; greatest thickness observed 2 mm. Cells tubular, cylindrical, 

 at right angles to the surface, non-septate, or septa very infrequent. Inter- 

 cellular space vesiculose ; vesicles near the base large and very irregularly 

 disposed, more regularly superimposed above and sometimes, when the cells 

 are closely disposed, appearing as septa dividing the space between the cell 

 tubes, but never, in the specimens observed, having the appearance of walled, 

 septate tubuli ; twenty-five or thirty septa in the space of 5 mm., measured 

 longitudinally. Cell apertures obscurely trilobate, length .40 mm., width 

 two-thirds the length, irregularly disposed, usually distant a little more than 

 the width of an aperture. Peristomes strong, nearly equally elevated. 

 Inter-apertural space flat, smooth, when slightly worn or macerated occupied 

 by shallow angular pits. Surface marked by broad, slightly elevated mon- 

 ticules, the centres of which are distant from each other between 6 and 

 7 mm., with a small, flat and smooth central area, the apertures immediately 

 adjacent are slightly larger than the others. 



