254 TABULATE CORALS. 



and in his last important work upon the corals (Hist. Nat. des 

 Cor., i860), M. Milne-Edwards adhered substantially to the 

 above arrangement, except that Stenopora, Lonsd., is now not 

 regarded as a well-characterised type. 



In the sense in which it is here employed, the family 

 Ch/rtetidce corresponds in the main with the " tribe " Ch(xtetincB 

 of Edwards and Haime. Stenopora, Lonsd., is, however, now 

 placed among the Favositida; ; Labechia, E. and H., is regarded 

 as the type of a special group ; and Fishilipora, M'Coy, and 

 Prasopora, Nich. and Eth., jun., are temporarily added to the 

 family, to take their proper place beside MonticuHpoi'a. Thus 

 constituted, it must be at once admitted that the family is an 

 artificial and unnatural assemblage, the retention of which, as a 

 single group, can only be defended upon the ground of our at 

 present imperfect knowledge of the structure and real relations 

 of many of the forms included in it. It is clear, indeed, that 

 the forms here provisionally associated under the family 

 ChcetetidcE agree with one another only in the general fact that 

 they possess coralla composed of closely contiguous corallites, 

 which are without septa, are traversed by tabulse, and have 

 imperforate walls. This last character, however, cannot be 

 regarded as sufficiently established for all the forms now under 

 consideration. Some of them almost certainly possess noth- 

 ing of the nature of the " mural pores " of the Favositidcs, and 

 none of them have been actually proved to possess openings 

 of a similar nature to the above. It is not impossible, how- 

 ever, that some of the genera at present placed in the Chcstetidce 

 may yet be demonstrated to possess " mural pores ; " and I 

 have myself examined a coral from the Wenlock Limestone of 

 Dudley, which is closely similar to Alontictilipora, D'Orb., in 

 form and general appearance, but in which the walls are in- 

 dubitably porous. Moreover, an examination of the minute 

 structure of the forms here included under the Chcetetidce 

 renders it clear that they admit of separation into two groups, 

 of very different size, and perhaps of a very different nature. 

 In the one group — which we may speak of as the ChcEtetida: 



