522 REPORT OX THE XEXIIDAE COLLECTED BY DR WILLEY. 



more than half-way towards the tip of the tentacle. In the distal portion of the tentacle 

 the bases of the pinnules of the two sides are close together in the middle line. (See 

 Fig. 3.) 



Spicules occur in considerable numbers in the body of the polyp, especially near its 

 distal end around the bases of the tentacles. (See Fig. 6.) They are more numerous 

 in the tentacles and they are so abundant on the outer face of the pinnules that they 

 are practically in contact with each other. (See Fig. 5.) The spicules are discs generally 

 oval in shape. The fully formed ones are •2mm. — -22 mm. m length, -OlS mm. — '018 mm. 

 in breadth, and •004 mm. in thickness. They are white or slightly bluish-white by 

 reflected light but reddish-brown by transmitted light. 



The stem of the colony is a pale yellowish-green colour (in spirit) but the pol}7)s 

 are whitish with a pale bluish " bloom," due to the very numerous spicules which 

 they contain. 



Habitat. Talili Bay, Xew Britain. (Specimens taken from trawl, 1895.) 

 Lifu, Loyalty Islands. (November, 1896.) 



HABITS, DISTRIBUTION AND CLASSIFICATION. 



The Xeniidae have been recorded fi-om the Red Sea and the tropical parts of the 

 Indian and Pacific Oceans. They are not recorded from the shores of America and 

 apparently they do not occur on the reefs near Jamaica, for although careful search 

 has been made on these reefs no specimens of Xenia have been hitherto found. They 

 are all littoral forms living in shore pools or in shallow water (3 — 6 fathoms), fixed 

 to the surface of coral reefs or hanging from the under side of hollow rocks or coral 

 boulders. They are often exposed at low water, and in those species in which the 

 polyps are long and slender the polyps fall together into a shapeless mass on the retreat 

 of the tide. They exhibit great variety and beauty of coloration; blue, green, brown, 

 and yellow are the predominant colours, though two species are reddish in colour. 



Several of the species of Xenia founded by various authors have been subse- 

 quently proved to be invalid : Lamarck's Xenia purpurea is certainly not a true 

 Xenia but is probably a Spongodes : Schweigger's Xenia esperi and Sars' Xenia 

 indivisa from Naples do not belong to the genus Xenia. Duchassaing and Michelotti 

 described Xenia carybeorum and ,X. capitata from the West Indies, but tliese also are 

 not members of the genus Xenia, as they differ completely in their general characters 

 and in their .spicules. The former has been renamed Erythropodium carybeorum by 

 Kolliker. 



The descriptions of several undoubted species of Xenia which have been given 

 are not sufficiently detailed to enable these species .to be again recognised and for 

 all practical purposes they must be set aside, at least for the present. Such are the 

 descriptions of Cornularia imdtipinnata (which is probably a true Xenia) by Quoy 

 and Gaimard, X. samoensis, Kolliker, X. ochracea, Sav. Kent, X. brunnea, Sav. Kent, 

 and X. pidsitans, Sav. Kent. 



