54 THE VOYAGE OF H.M.S. CHALLENGEE. 



is placed in the centre of the tunnel. The second row consists of two scale-like spicules 

 which tightly embrace one-half of the body of the polyp, the everted edges are triangular 

 in shape, these measure about 1 "5 mm. in length by 1 mm. in width. The third row also 

 consists of two scales about 1 mm. square, with everted frill-like margins. All these 

 three series are doubtless movable on one another. The opercular series of from six to 

 eight triangular-shaped scales are remarkable, in that those nearer the axis are less 

 calcareous and less fuUy developed than the outer ones, so that this portion of the 

 polyp is, when in a fully expanded condition, nearly naked. 



The spicules of the coenenchyma are oblong thickened scales, arranged side by side, 

 not imbricated, very feebly tuberculate or granular (tubercles or granules striate), some- 

 times slightly irregular branched. Measurements, l'3-0"2 mm. in narrowest and 0"302 

 in broadest end ; 0-804-0-3 ; 0-4-0-106 ; 1-204-0-404; 0-402-0-102 ; 0-402-0-1 mm. 



The spicules of the polyp bodies are very irregular in form. Those of the two ad- 

 joining lateral polyps on each whorl have been already referred to. They are in 

 shape somewhat like the clawed petal of a pink, and in the drawing (PI. XIV. fig. 5) are 

 seen in profile. The blade or expanded portion is 2 mm. broad by 1 mm. deep, and the 

 claw-Uke part is 1*5 mm. long ; it is placed at an angle to the blade, but its base is nearly 

 as broad as the broadest part of the blade. The outer spicules of the inner polyps are 

 much smaller and less winged. Some of the opercular spicules are triangular and keeled, 

 others are folded on themselves. When they, on the withdrawal of the tentacles, 

 approach one another, the larger and outer four fall over the inner series and become 

 themselves slightly imbricated like the petals in a papilionaceous corolla. The larger 

 opercular scales measure 1-0 '5 ; l'3-0"6 mm. The polyp tentacles have some needle- 

 like spicules, about 0*3-0 '02 mm. 



This remarkable form, in the peculiar bilateral arrangement of its whorls of polyps 

 upon the main axis, recalls to some extent CaUozostron. 



Habitat. — Reefs, Fiji. (This is almost certainly a deep-sea form.) 



Genus 2. Stachyodes,^ n. gen. 



Axis sparingly and dichotomously branched, consisting of a dense horny matrix, with 

 calcareous particles intermixed in the older portions, highly iridescent. Pol}"ps in closely 

 arranged verticils, about five in each verticil, tentacles retractile, when retracted the 

 opercular scales touching the basal scales of the lower row of polyps. Polyps with oral 

 region opening downwards. Spicules of the bodies of the polyps in three series of two 

 each, the spicules of each series either touching each other or overlapping, and 

 symmetrical. 



