A. E. Verrill — Bermudian and West Indian Beef Corals. 71 



A very extensive series of this species was collected, in 1S98 and 

 1901, in order to study its variations. Over 300 specimens of all 

 sizes from less than half an inch up to over five feet in diameter 

 -were studied by me. 



The variations are very great in several directions : — as in the 

 modes of growth ; breadth and depth of the actinal grooves ; and 

 especially in the breadth of the intervening ridges and of the inter- 

 mural or exothecal groove at their summits. The length, direction, 

 and arrangement of the grooves and ridges vary in every possible 

 way, often presenting the most diverse arrangements on different 

 parts of a single large specimen, especially if it has grown in a more 

 or less crowded or restricted position. 



These common variations include those forms that have been 

 named Dlploria Stolcesi Edw. and Haime, but which differ in no 

 way from the typical forms, except in having unusually wide ridges, 

 surmounted by a deep intermural groove, which often expands, 

 especially at the end of a ridge, to the breadth of 10 to 15 mm . 



Extracalicinal budding frequently occurs in these wide intermural 

 grooves. In life, many of these grooves show a distinct mouth, or 

 a series of mouths, with rows of tentacles, before any marked 

 changes occur in the underlying coral. But soon the bottom of the 

 groove receives deposits of columellar tissues, and then paliform 

 lobes and septa rapidly appear. Thus after a short period of growth, 

 these grooves become true actinal grooves formed over the exothecal 

 tissues of the walls, by true budding. They often become as deep 

 and well formed as the other furrows before they break through, at 

 one or more places, and thus become connected with the older 

 grooves. Some of them, both long series and single calicles, may 

 remain isolated for a long time in some specimens. 



As a matter of course, actinal grooves formed in this way must be 

 separated for some time by simple walls only. This accounts for 

 many of the cases where simple ridges are found mixed with double 

 ones on the same specimen (pi. x, fig. 1). A single ridge may also, 

 on this account, be double for a part of its length and single in other 

 parts, or it may divide into two simple ones, in certain places.* 



* Probably some of the confusion in respect to the synonymy of this species 

 is due to the fact that this mode of growth has not been recognized by authors, 

 and therefore specimens of this species with simple ridges have been referred to 

 different species and to a different genus {Mceandrina), for such specimens have 

 all the characters of Mceandrina, as contrasted with Diploria. (See p. 67.) 



It is not improbable that the figures of M. labyrinthiformis Pourtales (op. cit., 

 Florida Reefs, pi. ix. figs. 10-12, 1880) were drawn from a specimen of this kind 



