EEPORT ON THE XENIIDAE COLLECTED BY DR WILLEY. 521 



(3) Their shorter pinnules, the length of which is '2 mm. — 'So mm. compared with 

 •35 mm. — '5 mm. in X. Garciae. 



The pinnules of these two forms also differ in their shape and in their position 

 on the tentacle. The pinnules of Dr Willey's specimens are not only shorter than 

 those of X. Garciae but they are quite rounded at their tips, while those of the latter 

 are almost pointed. On viewing the outer face of the tentacles of X. Garciae it is 

 at once noticed that the pinnules which are then visible arise close together near the 

 middle line (see Fig. 4 and 1896, Plate 12, Fig. 14). In this respect X. Garciae 

 differs markedly from Dr Willey's specimens and indeed from any other species of Xenia 

 hitherto described (except Bourne's specimen of A', coerulea, in which also the long 

 slender pinnules on the outer face of the tentacles arise moderately close to the 

 middle line). 



A comparison has been made above between the specimens from this collection 

 and the only two hitherto described .species to which they may be said to have any 

 resemblance and it is evident that although there may be certain superficial resem- 

 blances between Dr Willey's specimens and X. plicata and X. Garciae the former differ 

 in several important characters from these and from any other hitherto described species. 



It cannot be argued that these are young colonies, the polyps of which have 

 not yet attained their adult length and the tentacles of which have not yet acquired 

 their full number of pinnules, because even the colony from Talili Bay, the largest 

 polyps of which are considerably smaller than those of the colonies from Lifu, con- 

 tains sperm sacs which are almost, if not quite, ripe. (The diameter of these sacs is 

 ■28 mm., the diameter of the ripe sperm sacs of this species is about "32 mm.) Thus 

 these are not small polyps which would later grow into larger ones with longer tentacles 

 bearing more numerous and longer pinnules characteristic of some other species. They 

 are mature and have acquired all their adult characters. 



These specimens therefore belong to a new species to which I propose to give 

 the name Xenia Novae Britanniae as the first specimens were obtained from Talili 

 Bay, New Britain (in 1895). 



Diagnosis of the Species XENIA NOVAE BRITANNIAE. 



The colony is knob-shaped or dome-shaped, the polyps arise from the strongly 

 convex upper face of the stem. The stem of the colony is usually unbranched. (See 

 Fig. 1.) 



The measurements of the fully developed polyps are: — body 2'8 mm. — 4'5 mm. in 

 length (a few reach 5 mm.) and '8 mm. — 1-3 mm. in breadth, tentacles I'S mm. — 3'5 mm. 

 long and 7 mm. — 1"0 mm. broad. Each tentacle bears three rows of short rounded 

 pinnules on each side of the middle line. There are 8 — 12 pinnules in each row. The 

 first three or four transverse rows near the base of the tentacle are small wart-like 

 protuberances not more than '2 mm. long but the more distal ones consist of slightly 

 longer and more typical pinnules 2 mm. — 35 mm, long and 15 mm. — 2 nun. in diameter. 

 The pinmdes are longest near the middle of the tentacle and decrease slightly in size 

 towards its tip. (See Fig. 2.) There is usually in the middle line of the inner face 

 of each tentacle a narrow area free from pinnules which extends from the base rather 



