NORTH AMERICAN PALAEONTOLOGY. 265 



Nicholson, H. Alleyne — Goutiuued. 



pillars aad concentric lamiuie ; c. Variations in the structure of these ; 

 d. The interlaminar spaces; e. The zooidal tubes; /. The astrorhizie; 

 g. The astrorhizal tabulse ; h. The axial tubes ; i. The cpitheca ; j. The 

 surface ; k. The reproductive organs. 



III. Systematic position and affinities of the stroniatoporoids. 



IV. Sketch chissification. 



V. Families and genera of the stromatoporoids : (1) Actiuostromidse. (2) La- 

 bechiidiL'. (3) Stromatoporid;e. (4) Idiostromidie. 



VI. The nature of " Caunopora." 

 The following is a notice of the American genera and species : 



Actinosiromidw, Nich. 



Actinosiroma gen. nov., Stromatopora, Auctt. 



Clathrodictijon, Nich. and Mur. Type C. vesiculositm, N. and M. Clinton and Ni- 

 agara formation. lu America there is also C. ceUulosum N. and M. from the 

 Corniferous limestone. 



Stylodictyou, Nich. and Mur. Type S. columnare, Nich. From the Devonian of 

 North America. 



Lahechidcv, Nich. 



Labechia, Edwards and Haime, 1851. Type L. conferta, Lonsd. Two species at 

 least of Lower Silurian age occur in North America, L. Canadenxis, Nich. 

 and Mnr., Trenton limestone, and L. Ohioensis, n. s., Cincinnati group. 



Dictyostroma, Nich. Type D. undulatum. Niagara limestone. 



Beatricea, Billings. Types B. vudulata and B. nodiilosa. The balance of evi- 

 dence seems to the author to be in favor of regarding Beatricea as an ab- 

 normal type of the Stromatoporoids. 



Stromatoporida', Nich. 



Stromatopora, Goldf. (emend.). Type S. concentrica. Refers to this genus his 

 own genus, Bachystroma, from the Niagara limestone. 



Stroviatoporella, nov. gen. Type S. granulata, Nich. From the Hamilton and 

 Corniferous formations of western Canada. Refers to this genus probably 

 Stromatopora nuUiporoides, Nich., from the Devonian, and the allied or iden- 

 tical Cw)w>stroma iitcrustaiis, Hall and Whitf., from the Devonian. 



Syringostroma, Nich. Type S. densum. 'Nich. From the Devonian rocks of Ohio. 



Idiostromido', Nich. 



Idiostroma, Winchell, founded for the re3eption of /. cocspitosum and /. gor- 

 diaceum, from the Devonian rocks of North America. 



Considering that the embedded tubes constitute the essential feature upon 

 which Caunopora, Phill., and Diapora., Berg,, were founded, the author 

 thinks that the facts render it al)solutely certain that Ihese names can not 

 be retained as names of genera. 



Concludes that "the fossils ordinarily called ' Can tiojwr a' and ' Diapoi'a' are 

 the results of the combined growth of some stromatoporoid with some 

 coral, the former usually being a si^ecies o{ Stromatopora or Stromatoporella, 

 and the latter generally belonging either to Syriiujopora or to Aulopora 

 We must also conclude, however, that there are other fossils in general 

 aspect exceedingly similar lo the ordinary ' Caunopora,' in which the em- 

 bedded tubes really do belong to the organism in which they are found, as 

 we have seen to be the case in Idiostroma ocnlatum. In practice, therefore, 

 each individual specimen must, with our present knowledge, be judged on 

 its own merits, apart from all preconceived theories. Moreover, as the 

 ' Caunoporce ' and ' Diaporm ' show many points of interest which are quite 

 independent of any hypothesis as to their actual nature, I shall, where 

 needful, describe and figure any noticeable features in connection with the 

 ' CaMno/>ora-state ' of certain Stromatoporoids, irrespective of all theoret- 

 ical views as to the precise nature of this ' state.'" 



