520 REPORT ON THE XEXIIDAE COLLECTED BY DR WILLEY. 



fully developed ones being 2'8 mm. — 3'3 mm. long and 'Smm. — I'l mm. in diameter, 

 and their tentacles IS mm. — 2'1 mm. long and about '8 mm. wide. 



The colonies from Lifu are all very similar, being knob-like or dome-shaped 

 colonies, though one or two, e.g. B ami D ii. are rather flattened from above down- 

 wards, and hence the polyp-bearing summit of the stem in these examples is rather 

 less conve.K than in the others. The fully-developed polyps of all these are moderately 

 uniform in size and character. Their measurements are: — body of polyp 3 mm.— .5 mm. 

 long and '8 mm. — 1'3 mm. broad, tentacles 2-2 mm. — 3'o mm. long and '7 mm. — 8 mm. 

 (occasionally I'O mm.) wide. 



The colony from Lifu marked D i. consists of two .similar and almost equal 

 dome-shaped stems, the measurements of which are given in the above table (p. 519). 

 The stems are bound together at their bases by a thin membrane. 



Two rather irregular and flattened stems joined together at their bases by a 

 slender connection form the colony marked D il. In this colony also the two stems are 

 almost equal and the measurements given in the table apply to both. 



The largest polyps of this species are found on the colony marked D i. Several 

 of these are 8 mm. in length (body .5 mm., tentacles 3 mm.). 



These specimens do not agree with the descriptions of any of the known species 

 of Xenia. They differ from most other species in their smaller polyps and short 

 rounded pinnules, and the latter are also much fewer in number than in most of 

 the known species. In some respects these specimens resemble X. plicata, Schenk, 

 and X. Garciae, Bourne, but on careful examination several important distinctions are 

 recognised. Dr Willey's specimens differ from X. plicata, in — 



(1) Their smaller polyps, the body of which is 2-8 mm. — 4'5 mm. long and 

 "8 mm. — rS mm. broad (in A', plicata the corresponding measurements are 4 mm. — 

 5 mm. and l'-5 mm. — 2 mm.). 



(2) Their much shorter tentacles, which are onh' 1"S mm. — 3 5 mm. long, while 

 those of X. plicata are 5 mm. — 7 mm. long. 



(3) The smaller number of pinnules on the tentacles, there being only 8 — 12 

 in each row while there are 18 — 22 in each row in X. plicata. 



There are other differences, e.g. in the arrangement of the polyps on the summit 

 of the colony, &c., but the above are the chief 



After comparing Dr WilleyV specimens with Mr Bourne's figure and description of 

 X. Garciae, I was still in doubt whether the two might not be identical. Mr 

 Bourne has kindly lent to me his specimen of X. Garciae so that I have been able 

 to compare the two directly. Dr Willey's specimens certainly do not belong to this 

 species. They differ from it in — 



(Ij Their longer polyps, the body of which is 28 mm. — 45 mm. long (the 

 corresponding measurement in X. Garciae is 1"8 mm. — 3 mm.). 



(2) Their longer tentacles, which attain a length of 1"8 mm. — ^o"5mm. while those 

 of X. Garciae are not more than 2 mm. in length. 



