3° 



CHAPTER II. 



THE FAVOSITID^. 



The principal characters of this family have been already 

 given, and merely need brief recapitulation here. The coral- 

 lum — whatever its form may be — is usually composed of more 

 or less prismatic corallites, which are generally in complete 

 contact throughout, and have well-developed walls, which are 

 perforated by a greater or less number of " mural pores," or 

 apertures, by which the visceral cavities of contiguous pol- 

 ypes are placed in direct communication. There is no true 

 ccenenchyma, and the condition of the septa is extremely 

 variable, while tabulce are usually numerous and complete. 



As regards the above characters, the general form of the 

 corallum is for the most part either massive or dendroid ; but it 

 is sometimes lamellar or frondescent (some types of Pachypora 

 and Ccenites) ; and Ronmigeria, Nich,, affords an example of a 

 subfasciculate corallum, as to a less extent does also the genus 

 Vermipora, Hall. The corallites radiate from the base in the 

 massive forms, from an imaginary axial line in the dendroid 

 types, and from an imaginary axial plane in the frondescent 

 species ; and their general form is more or less conspicuously 

 prismatic or polygonal. This is seen in almost all those 

 coralla in which the corallites are closely contiguous {Favo- 

 sites, Lam., Syringolites, Hinde, Michelmia, De Kon., Nydo- 

 pora, Nich., &c.) There are species, however, even of such 

 forms as the above, in which the corallites are subcylindrical. 

 In other cases (^Alveolites, Lam., Ccenites, Eichw., and some 



