THE ALC YON ARIA OF THE MALDIVES. 481 



Calcium carbonate, and prolonged boiling in caustic potash does not soften the tubes or 

 permit of the isolation of the spicules. 



The anthocodiae are completely retractile, and when that part of the body-wall of a polyp 

 is examined which is situated at the junction of the anthocodia with the non-retractile 

 portion, a few isolated spindle-shaped spicules can be seen. These spicules are very different 

 in form to those of any species of Telesto that has hitherto been described, and it is 

 perfectly certain that they grow very rapidly in size until they become as firmly fixed or 

 fused together as are the spicules in the tubes of Tuhipora (Figs. 5 and 6). 



In Telesto trichostemma it will be noticed that according to Studer (23) it is only 

 in the " older parts of the colony " that continuous calcareous cylinders are formed. In 

 T. rubra, on the contrary, the spicules at the base of the verrucae of the youngest buds 

 are fused to form a continuous calcareous skeleton. The secondary branches and the young 

 pol}^s are given off from the axial polyps at an angle which is almost a right angle. 

 This is another feature in which the new species seems to be peculiar. 



The tentacles of the retracted polyps are, in spirit, snow white or pale yellow. They 

 exhibit a row of about eight pinnae on each side, and each pinna is supported by a curved 

 spindle-shaped spicule 0'14 mm. in length. There is also a series of rod to spindle-shaped 

 slightly tuberculated spicules on the aboral side of the rachis of each tentacle (Figs. 3 and 4). 



In the specimen of T. trichostemma in the same collection the tentacles are quite free 

 from spicules. 



The general surface of ectoderm of nearly all parts of the colony is destroyed by 

 the encrusting sponge. 



I am greatly indebted to Professor Topsent of Rennes for examining these sponges, 

 and very kindly sending me a report upon them. 



The sponge that occurs on the Mahlos atoll specimen is Prosuberites epiphytum (Lamarck). 

 Professor Topsent tells me further that the blue-green colour is due to the Beggiatoaceae 

 which frequently invade Terpis fiigax, and were named by Carter Hypheothrix coerulea. 



The sponge that occurs on the Mulaku specimen appears to be a new species of the 

 genus Leptosia. 



The characters of the new species may be diagnosed as follows : — Colony consisting of 

 single upright axial polyps bearing a few secondary branches of the same nature. Several 

 young polyps are borne by the main stem and secondary branches. All the polyps are 

 completely retractile, the young polyps forming verrucae about 2 mm. in height. The axial 

 polyps, branches, and verrucae 1'75 mm. in diameter in the Maldive specimens. Body-wall 

 of the axial polyps and verrucae supported by a firm, perforated, tubular, calcareous skeleton, 

 which is pink in colour. Very few free spindle-shaped spicules at the growing edges of 

 the tubes. External surface of the tubes marked by eight longitudinal ridges. Tentacles 

 of the polyps white or pale yellow, with eight or nine pinnae on each side supported by 

 white curved spindles ('14 x '015) and other spicules. Locality, Maldive Islands, 23 — 25 fathoms. 



Telesto trichostemma Dana (5); Wright and Studer (22 and 23). 



From Mulaku Atoll, 25 fathoms, fine mud and rubble, and Miladumadulu Atoll, 24 

 fathoms, from one of the eastern passages. 



G. II. 62 



