724 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxu. 



Type.—Q'Ai. No. 21226, U.S.N.M. 



The tentacles appear to be quite constantl}" 15 except for two speci- 

 mens which have 16, Thej are 20 to 25 mm. long when extended. 

 Occasionally one or more tentacles are considerably smaller than the 

 rest, but as there is no constancy in position, I suppose these repre- 

 sent regenerating members. Occasional!}' individuals are found which 

 have lost a tentacle and possess an incipient "bud" in its place. As 

 noted in the diagnosis, the numl)er of digits varies considerably, but 

 in the large tentacles it is usually over 50. The small number of 30 

 is found only on small tentacles above alluded to. If one is fortunate 

 in finding a tentacle with the digits extended, the web is seen to extend 

 slightl}^ beyond the middle of the digits. The longest digits are at 

 the middle of tlie tentacle, and thence they are graduated in size 

 toward either end, the smallest being proximad, where they cease 

 about 6 imn. from base. The surface of bod}' is very rough with 

 the anchors, but the surface of the perisome itself appears to be 

 smooth in decalcihed specimens. 



The calcareous ring is fairly stout and is composed of 15 pieces, 

 there being two interradials between each radial. Both are slightly 

 excavated on posterior border. The radials have a large perforation 

 on the anterior border and the interradials a simple sul)spatu]ate 

 process. The exact form is best appreciated from iigures. The car- 

 tilaginous ring is about 5 mm. wide and the perforations occur regu- 

 larl}' opposite each piece of the calcareous ring, so that the concave 

 posterior border of the piece forms the anterior edge of a perforation. 

 These perforations vary in size, even in the same individual, being 

 from 0.5 to 1.25 mm. long. In the dorsal mesentery is a single slender 

 madreporic canal, and in addition very man}' (upward of tifty) shorter 

 ones form a crowded series all along the ring canal. The latter are 

 curved or twisted and are about 0.5 to 1 mm. in length, usually less 

 than a millimeter. ' Polian vesicles are extremely numerous (125 in one 

 specimen), and in preserved specimens are often slender and filamen- 

 tous, forming a tangled mass of threads all around the ring canal. 

 At their base is the wreath of madreporic canals. Length of Polian 

 vesicles about 10 mm. or less. Gonad in a right and a left tuft. When 

 fully developed it extends nearly to middle of body. The long slender 

 rachis gives off at intervals a slender tuft of tubules, which is really a 

 single tul)ule three or four times dichotomously branched. Fairly 

 well developed retractor uuiscles are present. Ciliated urns are 

 aVjundant on mesentery near attachment to body wall. This portion 

 of mesentery in anterior part of body is finely perforated. 



The anchor plates are fairly broad for length, the latter being 0.285 

 to 0.298 mm. The exact form is best appreciated from figure. Usu- 

 ally there are six toothed holes, but occasionally one or two small per- 

 forations occur at broad end. A plate with one such is figured. (Plate 



