516 REPORT ON THE XEXIIDAE COLLECTED BY DR WILLEY. 



(2) The tentacles of these specimens are 5 mm. — 8 mm. long, while those of 

 Klunzinger's specimen are only 3 mm. — 5 mm. in length, but Dana states that " in 

 Savigny's figure the tentacles are a third of an inch long " (1848, p. 604), i.e. 8 mm. 

 The tentacles of Dr Willey's specimens agree very closely with the latter diagnosis. 



(3) There is a larger number (22 — 29) of pinnules in these specimens than in 

 Klunzinger's specimen (12 — 15), but this is readily explained when the greater length 

 of the tentacles of the former is considered. As shown in X. Hicksoni (1899, pp. 283, 

 284) there is a gradual and moderately constant proportional increase in the number 

 of pinnules as the tentacles grow in length, and the proportion which holds between 

 the length of the tentacles and the number of pinnules is almost identical in the 

 two s])ecimens under consideration. As shown above the larger polyps of Dr Willey's 

 specimens contain ripe ova, and therefore the polyps are sexually mature and have 

 probably reached their full size. There is no record of the maturity or other\vise 

 of Klunzinger's specimen, and it is possible that the poh-ps which he measured had 

 not attained their full size, which would account for the differences between his specimen 

 and those of Savigny in the size of the tentacles and in the number of their pinnules. 



4. Klunzinger's figure (1877, Tafel III. fig. 3 a) which shows a broad area free 

 from pinnules on the inner face of the tentacle does not agree with other diagnoses 

 of the species X umhellata, e.g. cf Dana, p. 605. " The papillae in the upper view 

 of the tentacle are separated by an extremely narrow line so that those of the two 

 sides almost meet at the base." The tentacles of the specimens from New Britain agree 

 with the latter description very closely. 



5. The stems are thicker and the whole colony has a rather stouter appear- 

 ance than most specimens of X. umhellata, but this may be due to the influence of 

 difi"erent external conditions and it is certainly not a sufficient reason for separating 

 this species from X. umhellata. 



It may therefore be concluded that although the specimens differ slightly from 

 Klunzinger's description there is no essential point of difference between them and 

 X. umhellata. The variations may all be accounted for by differences in age and habitat. 



Previously recorded from the Red Sea, where it is abundant in the shallow waters of 

 the coral reefs, growing on rocks or old coral branches. 



XEXIA VI EI BIS. ScHESK. 



This species is represented in the collection by a portion of a colony, which consists 

 of a single unbranched stem nearly half of which has been cut or torn away longi- 

 tudinally. The stem is very thick, soft and fleshy, and of nearly uniform diameter 

 along its whole length. It is 18 mm. long and 22 mm. wide at the free end. The 

 surface of the stem is almost smooth, but near the distal end slight longitudinal ridges 

 mark the position of the outermost or peripheral coelentera of the polyps. The summit 

 of the stem is almost flat or only slightly convex. 



The poh'ps are short and stout and moderately numerous. They are 4 mm. — 6 mm. 

 long and 1'5 mm. — 2 mm. broad, (a very stout polyp measures 2'5 mm. in diameter). 

 The tentacles also are short and thick, they are 4 mm. — 6 mm. in length and 1 mm. — 



