CORALS AND CORAL-ANIMALS. 



155 





a. 



added as indicative of its widely distributed, but, so far as is l<no\vn, exclusive Australian 

 habitat. 



One other representative of the Zoantharia invites brief notice. This species is remarkable 

 for the fact that it coincides in structure with what might be termed a skeletonless replica of the 

 compound coral, hereafter referred to under the 

 generic title of Mussa. The pol^'ps in this type are 

 flat, exceedingly irregular in outline, coalescing with 

 one another in such a manner that two or three 

 oral centres are frequently included in the same 

 tentacular system. The tentacles are exceedingly 

 short, in most instances minutely lobate, and developed 

 over the greater portion of the area of the expanded 

 disk. The life colours of the disk are a light greenish- 

 brown, the tentacles redder brown and white-tipped, 

 while the slightly-exposed inner lining of the oral 



opening is rose-pink. A single specimen only of Platyzoanthus mussoides, Nov. gen., n.sp. Ex- 



,, . . ^ ,. , , . , ^ , , p.inded colony-stock, -A natural size. At a, a 



this interesting type was obtained from beneath , , , 



tentacle enlarged. 



a reef-ledge at Vivien Point, Thursday Island. The 



individual polyps in this species, where enclosing only a single oral system, bear a consider- 

 able resemblance to those of Klunzinger's Cryptodendnim adhaesivnm, but with the shorter- 

 branched tentacles of Rhodactis rhodostoma, M. Ed., as figured in each instance by Andres. 

 Drawings of the type, submitted by the author to Dr. Playfair McMurrich, the American 

 zoophytologist, elicited the opinion that a compound form somewhat analogous to, although 

 different from the Australian type, in details of generic import, had been recorded from 

 the West Indian region by Duchassaing and Michelotti. It seems imperative here again 

 to employ both a new generic and a new specific title for its distinction, and it is, 

 accordingly, added to the list of Zoantharian species, in association with the title of Platyzo- 

 anthus* mussoides. Unfortunately, the space available for the illustration of the Zoantharia 

 has been found insufficient for the inclusion of more than the diagrammatic outline of this 

 interesting species given above. 



ORDER III.— MADREPORARIA. 



The order of the IVIadreporaria, or Stony-corals (as they are popularly termed, with 

 reference, to the more or less dense calcareous skeleton which they possess), necessarily repre- 



* Platiis, broad, Zoanthus. 



X 2 



