238 DR. J. E. GRAY ON ZOANTHIN^. [Feb. 14, 



and those on the lip and the edge of the shell are generally the 

 largest, as they are in a position where they can obtain the most 

 nourishment. They are gradually developed from the surface of the 

 coral that covers the shell. They first appear as a small circular 

 spot, which enlarges and gradually raises itself above the surface of 

 the surrounding coral until it forms a cylindrical body, which is 

 generally considerably higher than it is broad. The adult or well- 

 developed body sometimes breaks off from the base, leaving a cir- 

 cular concave scar, with pores round its circumference, which is the 

 basis of the ovaries of the animal. 



4. Gemmaria, Duchass. & Michel. Mem. Coral, des Antilles, 55. 



Mammillifera, sp. 



Pahjthoa, sp., Milne-Edw. Coral, i. 303. 

 Base expanded ; polypes not soldered together. 

 Duchassaing and Michellot describe several species of this genus ; 

 to these add 



Gemmaria? sulcata. 



Zoanthus sulcatus, Gosse, Brit. Sea Anem. 303, t. 9. f. 7, 1. 12. f. 2. 



Hab. Devonshire. 



Tentacles twenty-two, in two rows ; upper half of polypes naked. 



5. Palythoa, Lamx. Hist. Polyp. 361 ; Duchassaing & Michellot, 

 Me'm. Coral, des Antilles, 53, 1860. 



Palythoa a A & a a a, Milne-Edw. Coral. 304. 

 Cavolina, sp., Schweiger. 

 Corticifera, Lesueur. 

 Mammillifera, Ehr., Blainv. 

 The polypes soldered side by side. 



1. Palythoa mammillosa, Lamx. 



L. stellata, Lamx. 



Alcyonium mammillosa, Solander, Zooph. t. 1. f. 4, 5. 



2. Palythoa axinell^, O. Schmidt, Sponges of the Adriatic, 

 p. 61, t. 6. f 1, 2. 



Polype short, broad, on an expanded base, white when dry. 



Hab. Adriatic. Parasitic on Axinella cinnamomea and A. ver- 

 rucosa, O. Schmidt (Sponges of the Adriatic, pp. 61, 62). Esper 

 called the latter sponge Sjiongia vei'rucosa, from the presence of this 

 polype. 



Professor Oscar Schmidt described a species of Axinella which has 

 circular eight-rayed stars scattered on the surface and sunk in the 

 substance of the sponge, under the name of Axinella polypoides 

 (p. 62, t. 8. f. 5). He calls these stars oscules; but they are very 

 unlike the oscule of any other sponge, and I think they may be 

 parasitic actinioid poly^pes. Mr. Bowerbank, in his ' Bi'itish Sponges' 

 (t. 20. f. 307), figures a very similar body, which he describes as 



