NO. 1624. DESCRIPTIONS OF HAWAIIAN ALCYON ARIA— NUTTING. 575 



STENELLA HELMINTHOPHORA, new species. 



Plate XLIV, figs. 6-9 ; plate XL VII, fig. 5. 



Specimens much broken up. Colony evidently large, on6 stem being 

 13 mm, in diameter and densely calcareous. Branching not easily 

 made out owing to the greatly broken condition of the specimens. 

 Main branches irregularly distributed, branchlets dichotomously di- 

 vided, with a tendency for the twigs to lie in the same plane. 



Polyps irregularly distributed on main stem and branches, and in 

 irregular whorls of four on the terminal twigs, length about 4 mm., 

 shape cylindrical with a greatly expanded distal end, which flares 

 like the mouth of a trumpet. The calyces jDroject rigidly from the 

 stem at right angles. 



Spicules very large and squamiform, concave on cortex, with con- 

 vexity resting on stem or branch, less concave on calyx where the 

 scales are in about four whorls with three or four to a whorl. First 

 whorl longest, often consisting of but two scales ; third whorl shortest ; 

 the first, second, and third whorls forming a cylinder, but with their 

 distal edges often elevated and more or less frilled. The distal whorl 

 is much expanded at its margin, forming a cup composed of four 

 scales (two larger and two smaller) inclosing the operculum. The 

 operculum is composed of eight scales, each of which has a lamelli- 

 form raised edge, giving the appearance of eight vertical concentric 

 plates. The operculum extends considerably beyond the calyx wall. 



The spicules of the cortex are scale-like, fluted, often convex, with 

 the convexity attached to the stem or branch. 



Nearly all of the specimens were infested with an annelid, which 

 had", by its presence, modified the first whorl of body scales so that 

 they formed a sort of a tunnel, running along the branches, in which 

 the annelid lived. These modified scales are enormously enlarged, 

 two rows of them arching over and meeting each other above, form- 

 ing an arcade. These arcades cover the greater part of one side of 

 the branches in many specimens, and it is scarcely to be wondered at 

 that Wright and Studer took this arcade or tunnel to be a normal 

 structure." 



In several specimens small simple-armed basket fish were exces- 

 sively numerous, and these, too, seemed to have modified in some de- 

 gree the cortex scales. 



This species differs from Stenella spinosa in color of stem, and in 

 having much more slender polyps; and from S. johnsfoni in the 

 number of whorls of spicules, and in the operculum. 



<* Report on the Alcyonaria collected by H. M. S. Challenger during the years 

 1873-1876, p. 53. Here the authors regard this structure as a generic character 

 of the genus Calypterinvs, an error that has already been corrected by Studer. 

 (See Alcyonaires provenant des campagnes de rHiroudelle, 1886-1888, 1901, 

 p. 40.) 



