762 MB. J. STAHLBY GAEDINBR ON [,) Une 6, 



but some again are much larger, varying up to 3-5 mm. The costaB 

 are quite distinct, and the columella is, if present, extremely 

 rudimentary. 



Eotuma; boat-channel. 



Genus Q-alaxea. 



Oalaxea (pars), Oken, Lehrb. der Nat. i. p. 72 (1815). 



Qalnxea, Milne-Edwards & Haime, Cor. ii. p. 223 (1857). 



Most of the species in this genus are exceedingly ill-defined, and 

 it seems probable that most of the so-called new species, described 

 since Milne-Edwards and Haime's monograph, will prove to be 

 synonyms. All the ' Challenger ' species, with the possible exception 

 of G. explanata Quelch, I should refer to previously known 

 forms. 



1. Galaxea LAPEEOUSBAJiTA Milne-Edwards & Haime. 



Garcinula laperouseana, Milne-Edwards & Haime, Ann. des Sc. 

 Nat. ser. 3, x. p. 315, pi. vi. fig. 5 (1848). 



Galaxea laperouseana, Milne-Edwards & Haime, Cor. ii. p. 231 

 (1857). 



This species was first characterized by the irregularity in shape 

 of the calices, their size, and three complete cycles of septa 

 without any rudiments of a fourth, in all of which characters my 

 specimens agree. The central calices of the mass and hence the 

 oldest, as the budding is entirely from the edge, vary greatly in 

 size ; the largest I have found is 10*5 by 4'5 mm., while calices 

 immediately around it are 5*5 by 4*5 mm., 9 by 5 mm., 7 by 5 mm., 

 and 5'5 by 4 mm. The free portions of the calices vary up to 

 1*5 cm. in height above the peritheca, but are usually about 

 1 cm. The corallites are 2-3'5 mm. distant from one another at 

 the surface of the corallum. 



The primary and secondary septa are nearly equal in size and 

 from 2 to 4 mm. exsert. The tertiary septa are from 1 to 2-5 mm. 

 exsert, and generally are situated rather more externally than 

 those of lower orders. The costae of the tertiary septa are hence 

 sometimes more projecting, but there is " usually no marked 

 difference between the costse, all extending for about 2 mm. down 

 the theca. The outlines of the primary septa are as shown in 

 Milne-Edwards and Haime's figure, but the inner edge is commonly 

 rather more vertical. The primary and secondary septa fuse in 

 the centre of the calice, but there is no columella. 



The peritheca is very light and formed of thin loose arches of 

 corallum on one another. Its surface is continuous between the 

 corallites, but below this it is much bored into by organisms and 

 in places completely destroyed. 



Eotuma ; outer reef. Two specimens. 



The largest specimen is 15 cm. by 8 cm. and 9 cm. thick. It is 

 the growing edge of a large mass the central part of which has 

 been killed. Over a great part of the upper surface an incrusting 



