1899.] ASTRffllD COBAI/S FBOM 'HIE SOUTH PACmC. 737 



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

 the interseptal loeuli, which may he arranged, according to the 

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



1. MussA CACTUS Dana. 



Mnssa cactus, Dana, Zooph. p. ITS, pi. vii. fig. 1 (1848). 



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

 or three of those described by Milne-Edwards 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 figure and description: — "Disk green; inner 

 tentacles bursiform, 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 well-marked in my spirit speci- 

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

 corallnm, and below this there is a thin, inerusting 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 lamellse from the 

 septal edges, without any distinct surface spinulation. 



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



2. MussA OBisTATA Esper. 



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

 (1791). 



Mussa 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 costse 

 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 down 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. 



Eotuma; boat-channel. 



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



3. Mussa multilobata Dana. 



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

 Miissa multilobata, Milne-Edwards & Haime, Cor. ii. p. 336 

 (1857). 



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



