136 Cincinnati Society of Natural History. 



thick walled tubes, separated from each other by "one or two rows 

 of angular interstitial cells."* As the mode of growth can not be 

 used as a generic character, and as thick walls, interstitial cells in 

 rows, and spiuiform corallites are found in other genera {Lieoclema, 

 for instance, as well as others), neither can these be of any use 

 for this purpose. 



Aspidopora, Ul., forms very thin expansions with a concentric 

 and radially striated epitheca on the lower surface, and with an 

 upper surface composed of "from one to many unequal convex 

 spaces," the cells gradually increasing in size from the margin to 

 the center of each space. t Obviously, the striation of the under 

 surface, the difference in the size of the cells, and the "unequal 

 convex spaces,'' are not generic characters, though they might be 

 good specific ones. 



Dckayia, Ed. and H., has long been a recognized genus of 

 the group, though the grounds upon which it is separated from 

 Monticnlipora are, according to Dr. Nicholson, "purely arbitrary," 

 and consist mainly in the presence of numerous well marked spini- 

 form corallites, projecting above the surface of the cell apertures. + 

 It may be allowed to stand at present as a sub-genus. 



The same can not be said of Dekayella, UL, for this has in- 

 terstitial tubes (wanting in JDckayia^ a.r\6. a greater numberof spini- 

 form corallites, § a character found also in Batostoma, Batostomclla, 

 Leioclema, Atactopora and others. 



Petigopora, Ul., is proposed for certain species forming small, 

 irregular patches on the surfaces of shells or corals, the main char- 

 acters being "(i) the large and numerous spiniform tubuli; and (2) 

 the limitation of the growth of colonies to small individual patches, 

 which if brought into contact by lateral development, do not fra- 

 ternize, but either raise a non-poriferous barrier, or have a nar- 

 row, unoccupied space between them."|| Here, again, we have 

 habit and the uncertain spiniform corallites made to characterize a 

 genus, and again we protest against making specific characters 

 equal to generic ones. 



Nebulipoia, McCoy, presents no features to distinguish it from 

 Monticnlipora, and it, with the others, is reduced to a synonym. 

 Dr. Nicholson considers it to be "unquestionably congeneric" with 

 Monticulipora. *^ 



*J. C. S. N. H.'v., 154. 

 + Ibid v., 155. 

 IGenus Monticu. 99. 

 §Ulrich loc cit v. 155. 

 ||Ibid vi.. 156. 

 lIGenus Montic. p. 2. 



