72 A. E. Yerrill — Bermndian and West Indian Reef Corals. 



This mode of increase, by exothecal budding, seems to occur most 

 freely in young specimens 2 to 8 inches in diameter, though not 

 exclusively so. In such specimens the ridges are often all or nearly 

 all broad and deeply grooved, or just ready to divide (plate x, figure 

 3). Others, scarcely larger, may be found in which all or nearly all 

 the ridges are narrow and single, without grooves, the divisions 

 having already taken place (pi. x, fig. 2). Specimens in both these 

 stages, and in various intermediate conditions, were collected by me 

 ill Bermuda, both in 1898 and 1901. 



The stage in which broad and deeply grooved ridges occur has 

 been named as a distinct species [J)iploria StoJcesi) by Edwards 

 and Haime. Some later writers have called it a "young stage"; 

 others have called it a variety. It appears, from the facts just 

 stated, that is is only a j)hase of growth, which may occur at various 

 stages of development. M. truncata Dana seems to have been based 

 on a phase following the division of the ridges and before the new 

 grooves had developed on their summits. Such specimens are not 

 rare. See pi. x, fig. 2. 



Large specimens occur in which one part will show the /Slokesi 

 arrangement, while another part will be of the typical form ; and 

 still other parts will present simple or nearly simple solid ridges of 

 the truncata. phase. See pi. x, fig. 1. 



Many oblong specimens show, especially on the sides, many long 

 and nearly parallel, subradial, or nearly transverse ridges- and 

 grooves, while on other jjarts they present the ordinary convoluted 

 arrangement. 



The gyri are often in places more or less angular or zigzag, esj^eci- 

 ally on the median or more ci'owded portions, thus showing that the 

 form recently described and figured by Whitfield as D. geographical 

 is only a form of growth, not of varietal value. 



Many of the larger hemispherical and oblong examples consist of 

 two, three, or more originally separate masses that have come in 

 contact by growth and crowding, and have then grafted them- 

 selves together completely. The planes of union are usually shown 

 only by a thin line of epithecal tissue. Some of these double speci- 

 mens are as evenly and regularly hemispherical as the simple ones. 



and not from M. cerebrum, as Vaughan supposed. The types from which the 

 original plates of that Report were drawn were not separately preserved nor in 

 any way indicated by labels. While I had charge of tlie coral-collections of the 

 Mus. of Comp. Zoology (1860-1864), I tried in vain to identify the specimens 

 that had previously been figured on those plates, which were then unpublished. 

 Therefore any question of synonymy must be settled by the plates themselves. 

 Fortunately they are very accurate. 

 * Bull. Amer. Mus., xiv, p. 223, 1901. 



