REPORT ON THE XENIIDAE COLLECTED BY DR WILLEY. 5 1 1 



of the somewhat short and wide tentacles hears on its inner face three rows of pinnules 

 on each side of the middle line. There are nine to twelve pinnides in each row. In 

 the majority of the polyps the pinnules occupy the whole of the inner face of the 

 tentacle with the e.xception of a small area in the middle line near the base. The 

 pinnules, which are rather stout and conical, are o mm. — '7 mm. in length and '2 mm. 

 in width. 



Besides these well-developed polj'ps there are man}' buds or young polyp.s in 

 various stages of development. These are situated not only round the outer edge of 

 the polyp-bearing summit of the stem, where thej' are most usually found in other 

 Xeniidae, but are also scattered over the convex end of the stem between the bases 

 of the larger and older polyps. The buds are, however, much more numerous round 

 the edge of the convex disc, there being about thirty polyps less than one millimetre 

 in length situated around this edge. In the youngest polyps, the length of which is 

 "4 mm., the tentacles are indicated by eight small rounded elevations separated from 

 each other by slight grooves. In slightly older polyps '7 mm. long the tentacles are 

 simple rounded wart-like elevations "3 mm. high. The first pinnules appear when the 

 tentacles of the polyp attain a length of about 4 mm., and from this stage onwards 

 there is a gradual increase in the number of jDiunules along with the increase in length 

 of the tentacle, e.ff. a tentacle '5 mm. long shows when seen from the outer aspect 

 three pinnules on each side of the middle line, a tentacle '75 mm. long shows five 

 pinnules, one '9 mm. long shows six pinnules, &c. 



The disc-like spicules are extraordinarily numerous, and in many parts they are in 

 contact with or even overlapping each other. They are whitish by reflected light and 

 either light yellow or light reddish-brown by transmitted light. Most of them are oval 

 in shape but some circular ones are present. They are 018 mm. — 024 mm. in length 

 and '015 mm. — "018 mm. in breadth. 



The stem of the colony is light yellow-brown, slightly tinged with green in the 

 upper part, the polyps are a much lighter shade of the same colour. The greyish- 

 white colour of the tentacles and pinnules is probably due in a great measure to 

 the light reflected from the very numerous spicules present in those parts. 



The specimen is a male but the gonads are small. The sperm sacs are recognisable 

 as .spherical swellings on the edges of the six ventral and lateral mesenteries, but 

 the largest sacs present are only "08 mm. in diameter, and are obviously in an early 

 stage of development, the cells which they contain having undergone comparatively 

 few divisions. These sacs are similar to the largest of the three of X. Hicksoni 

 represented on PI. 27, Fig. 30 (1899). 



Two large polyps were stained and cleared. The stomodaeum of these polyps 

 is about '9 mm. long, and the wall of each shows a considerable number of small 

 light areas which probably indicate the presence of swollen empty cells similar to 

 those which have been described in the stomodaeum of X. Hicksoni (1899, p. 251). 



Habitat : — Isle du Phare Reef, Noumea, New Caledonia. 



The specimen agrees in most respects with the diagnosis of A', crassa, Schenk (1896, 

 p. .58), but the dimensions of the polyps of Dr VVilley's specimen are about two-thirds 

 those of Schenk's specimen and the number of pinnules on the tentacles differs 



68—2 



