1899.] ASTB^ID CORALS FROM THE SOUTH PACTFIC. 737 



of the endotheea in all is very similar, forming thin plates across 

 the interseptal loculi, which may be arranged, according to the 

 form of growth, in almost any position from horizontal to vertical. 



1. Muss A CACTUS Dana. 



Mussa cactus, Dana, Zooph. p. 178, pi. vii. fig. 1 (1848). 



I have referred seven specimens to this species, with which two 

 or three of those described by Milne-Edv^ards and Haime would 

 also seem to be identical. All the specimens were obtained from 

 the same locality, and in the colour of the living polyps conformed 

 perfectly to Dana's fit,nire and description : — "■ Disk green ; inner 

 tentacles bm-siform, pearl-white, and brown at tip, outer a little 

 elongate and brown." The broad pad of tissue in the contracted 

 polyps round their edges is very \^ell-marked in my spirit speci- 

 mens as in Dana's figure. The corallites, however, tend to be more 

 irregular in outline, and form in the centres of the colonies longer 

 series than are represented by Dana. 



The polyp extends for 1-1-5 cm. down the outside of the 

 coralliim, and below this there is a thin, incrusting epitheca. The 

 costse are marked solely by a few, upwardly directed, pointed spines 

 about 1 mm. high and 3-4 mm. distant one from another. The 

 columella is well marked, and formed of twisted lamellae from the 

 septal edges, without any distinct surface spinulation. 



Eotuma ; found only in certain reef-pools otF Solkopi. 



2. Mussa ceistata Esper. 



Madrepora cristata, Esper, Pflanz. i. p. 150, Madr. pi. xxvi 

 (1791). 



Mima cristata, Milne-Edwards & Haime, Cor. ii. p. 335 (1857). 



I have referred four specimens to this species, which agree fairly 

 well with the above descriptions. They do not bear, however, much 

 resemblance to Esper's figure, the spinulation of the septa not being 

 different from that of other members of the genus, and the costje 

 not being so marked, although without spines as in the figure. The 

 polyps extend for 1-5-2 cm. down the outside of the corallum, and 

 the ribbed appearance below their edges is in one specimen nearly 

 as distinct as in Esper's figure. These ribs appear to be due to 

 the retreating polyp laying do^:^'n a thin epitheca behind it, which 

 in places forms arches over the costae, which themselves broaden 

 out. The columella is well developed and of a spongy structure, 

 with no spinulation on its surface. 



Botuma; boat-channel. 



The living polyps are of a light olive-green colour. 



3. Mussa multilobata Dana. 



Mussa multilohata, Dana, Zooph. p. 181, pi. viii. fig. 2 (1848). 

 Mussa multilohata. Milne-Edwards & Haime, Cor. ii. p 336 

 (1857). 



This identification is, like that of Mussa cactus, largely based on 



