GENERA OF FAVOSITIDM. 153 



terlor of the tubes. New corallites produced by gemmation 

 from the hollow periodic expansions in the intervals between 

 the old cups. 



Obs. — It is perhaps impossible for any one who has not 

 access to the original examples of Chonostegites Clappi, E. and 

 H., and Michelinia intei^mittens, Bill., to entirely and finally 

 unravel the confusion in which the present genus is enveloped. 

 I shall, however, briefly state the conclusions at which I have 

 arrived upon this subject, and some of which I regard as quite 

 certain. 



The genus Chonostegites was founded by Milne-Edwards and 

 Haime for the reception of a coral unquestionably possessing 

 the general characters given in the above generic diagnosis, 

 which is based upon specimens of the coral described by Billings 

 under the name of Hawieophyllum inordinatum. They state 

 that their specimens are of Devonian age, and that they were 

 found in the drift of Dayton in Ohio. Under these circum- 

 stances it cannot be doubted but that the original specimens of 

 Chonostegites Clappi^ E. and H., were derived from the Corni- 

 ferous Limestone, the silicified corals of this formation beingf 

 abundantly distributed in the drift of various parts of the 

 Northern United States. 



At a later date, in 1859, Mr Billings described two corals 

 from the Corniferous Limestone of Canada, under the names of 

 Michelinia intermittens and Haimeophylhwi inordinatum^ the 

 latter being made the type of a new genus. With regard to 

 Michelinia intermittens, Mr Billings himself expresses a doubt 

 if it be truly separable from Chonostegites Clappi, E. and H., 

 adding that in this case the species should stand as Michelinia 

 Clappi. This opinion on the part of Mr Billings was based 

 upon the observation that in those portions of the corallum of 

 M. intermittens in which the corallites are in contact they are 

 prismatic in shape, and that they possess mural pores. On the 

 other hand, Haimeophyllum is founded for a coral which is said 

 to differ from Michelinia only in the fact that the corallites are 

 not in close contact, are subparallel, and are united by the coal- 



