GENERA OF FAVOSITID^E. 123 



secondary deposit of sclerenchyma. As has previously been 

 pointed out, this is the case with the so - called Alveolites 

 Fischeri, Bill., and A. frondosa, Nich. ; and I have no doubt 

 that other forms, both of the expanded and ramose type, will 

 ultimately prove to be referable to Pachypora, rather than 

 to Alveolites as here defined. 



3. The forms grouped under C&nites, Eichw., so far as pro- 

 perly placed under this head, may be distinguished from 

 Alveolites by the form of the calices, but more especially by 

 the great thickening of the interior of the tubes in the neigh- 

 bourhood of their mouths. As will subsequently be seen, 

 therefore, Ccenites bears the same relation to Alveolites that 

 Pachypora does to Favosites, while it has some special features 

 in addition. 



4. The forms which have been described as Alveolites septosa, 

 Flem., and A. depressa, Flem., are closely allied to Chcztetes 

 radians, Fischer, and must be removed to the genus Chtetetes. 



Returning now to the genus Alveolites as here defined, the 

 form of the corallum appears to be very variable. Alveolites 

 sub orbicular is, Lam., the type of the genus, appears really to 

 be almost always in the form of irregular masses which are 

 formed of concentrically disposed layers which have grown 

 parasitically round some foreign body. In other forms, how- 

 ever, such as A. Labechei, E. and H., and A. Goldfussi, Bill., 

 the form of the corallum is that of a flattened, sometimes gib- 

 bous expansion, which is covered below by a wrinkled epitheca, 

 and only exhibits calices upon its upper surface. Other forms, 

 again, such as A. Rcemeri, Bill., are dendroid ; but the various 

 ramose corals which have been included under Alveolites will 

 require to be subjected to a careful microscopic examination 

 before their true affinities can be positively asserted. Lastly, 

 so far as I have seen, no true Alveolites, in the sense here 

 understood, has the form of an erect frondose expansion, 

 attached basally, and having its free surfaces entirely covered 

 with calices. 



