714 PROCEEDINGS OF THE NATIONAL MUSEUM. vol xxxii. 



usually ending in about four teeth to each rod; many tables having 

 symmetrical disks with numerous perforations; in pedicels numerous 

 modified tables with elongate, curved, rod-like disk broadened in cen- 

 ter with four perforations and with either extremity narrowed, spat- 

 ulate, and perforated with numerous small holes; spire much as in 

 normal tables; tables, unlike those of preceding species, very densely 

 crowded. At base of tentacles are a few rods with expanded, much 

 perforated extremities, these becoming oblong, oval, subcircular, or 

 regular perforated plates in perisome surrounding base of tentacles, 

 many with and man}'^ without spires, and grading into normal tables 

 in neck. Color in alcohol whitish, tube feet yellowish. Length, 20 

 mm.; greatest breadth, 6 mm. 



Locality. — Station 4044, west coast of Hawaii Island; 233 to 198 

 fathoms, fine gray sand, bottom temperatue 47"^; 1 specimen. 



Ty/x.—C2it. No. 21224 U.S.N.M. 



The larger tentacles are 4.5 mm. long, the smaller about 1 mm. Of 

 course in life these dimensions would be somewhat greater. The body 

 wall is considerabl}" wrinkled, so that it is probable that the animal is 

 considerabl}^ contracted. The entire absence of pedicels on the two 

 ventral interambulacra and the fairly regular arrangement along the 

 three radii of trivium, especially the midventral, gives to the species 

 the general appearance of Cucumaria. The tentacles, however, are 

 typical of Thyonidium. The calcareous ring is large (8 mm. long) 

 and the radial pieces have long posterior prolongations which are 

 composed of many irregular plates. These prolongations of adjacent 

 radial pieces are fused for a part of their length, the interradial pieces 

 being small and wedged in between anterior portions of radials. For 

 exact form see Plate LXXII, fig. 3. One madreporic canal and one 

 Polian vesicle. Gonad very large; tubules unusually short, thick, and 

 branched once or twice. 



The tables with regular disks have a major diameter of about 0.086 

 to 0.1 mm. (Plate LXXX, fig. 3«), this type being very similar to the 

 normal tables of the preceding species. The larger irregular disks 

 attain 0.012 mm. (3Z»). Spires are about 0.057 mm. high, the two 

 uprights being joined by a crossbeam near summit and each ending in 

 about four to six teeth. Occasionallj' the upper crossbeam is absent. 

 Figures 3c and 3c? show the type of table which crowds the pedicels. 

 Many are less regular than this, being curved in the plane of the disk 

 as well as in that of the spire. End plates of pedicels have a diame- 

 ter of about 0.24 mm.; perforations numerous, rather larger about 

 peripher}^ than in center. 



This species differs from hawaiiense in the following respects: Shape 

 of body, thickness of perisome, color, distribution of pedicels and 

 their larger size, presence in pedicels of modified tables, very crowded 

 condition of deposits, character of tables, presence of a few rods in 



