THE STJBPAMILT ASTBAWGHAOE^. 397 



ridges and bending at sharp angles between the calicles. The 

 calicles are circular or slightly subcircular, maximum diameter 

 7 millim. Tertiary septa dentate above ; all septa with approxi- 

 mately vertical inner margin ; surfaces of the first three orders 

 in a few cases sparsely and finely granular. 



Increase of the colony takes place by gemmation, either (a) from 

 the sides of older corallites, the interseptal cavities of the older 

 and younger being (in some cases at any rate) in communication ; 

 (&) from the basal stolon (see fig. 10). 



I would call special attention to (1) the variability of the cen- 

 tral columellar mass in large corallites from (i.) a continuous dome- 

 like calcareous mass from which the columellar pillar and the pali- 

 form septal lobes rise prominently, to (ii.) a spongy aggregation of 

 plicate laminse, the upper margins of which are scarcely resolvable 

 into distinct columellar columns and paliform lobes ; in other 

 words, from tJie papillose to a trabecular type ; and (2) to the 

 variation in the source of the gemmation, viz. from the stolon to 

 the sides of the calicles ; MM. Milne-Edwards and Haime state 

 that in this group the former mode alone obtains. Verrill (Tr. 

 Conn. Ac. i. p. 525) has already pointed out that in Astrangia 

 both methods occur. 



Phyllaistgia dispbesa, Verrill, var. (Plate XYI. figs. 1-4.) 

 Phylkngia dispersa, Verrill, Bull. Mus. Camp. Zool. i. p. 4] ', Trans. 



Conn. Acad. i. p. 632. 

 In a specimen coating the umbonal region of a bivalve shell 

 from deep water, Malacca, in the National collection, the common 

 basal lamina is thin ; in one case a good-sized corallite rises 

 from the lamina in such a way that the wall is continued by 

 a gradual curved sweep into the lamina, on to which some of 

 the costse are faintly continued; the remaining corallites rise 

 abruptly from the lamina, and the costse can rarely be distinctly 

 made out to be continued on to the lamina. Although some of 

 the calicos are of fair size, viz. 5*5 millim. in the greater diameter, 

 this wall is very thin, and the maximum height is only 4*5 millim. 

 The calicles vary from a circular to an elliptical form, the dispro- 

 portion of the axes in the latter reaching as much as 11 : 9 ; 

 the costse are either (i.) low, extending to the foot of the corallites 

 — those of the primaries, and sometimes of the secondary septa, 

 standing further out from the wall than the rest — or (ii.) they are 

 subequal, or (iii.)they are wanting (on one part of a corallite). The 



30* 



