NO. 1555. HAWAIIAN HOLOTHURIANS— FISHER. 713 



Nearly all the tables of general perisome have the disk similar to tig. 

 2(/, Plate LXXIX. This varies in diameter from 0.()75 to U.095 mm. — 

 not a great range. Usuallj- one diameter is slightl}" greater than the 

 other. The spire, which commonly has an irregular crown, ends in 

 two to four teeth, and is about <».()(> mm. high. Ta})les are not at all 

 crowded in perisome, but are well spaced. End plates of pedicels are 

 circular and have a diameter of 0.135 mm. The numerous perfora- 

 tions decrease slightly in size toward periphery. The modihed tables 

 near base of tentacles have a major diameter of 0.1 to OA"! mm. The 

 spires var}" considerably in height, but seldom exceed those of regular 

 tables. Comparatively few of the latter appear to lack a spire 

 entirely. In perisome between mouth and l>ase of tentacles are 

 numerous rods much branched and forming rosettes, or the l)ranches 

 join, forming ii-regular perforated plates. They are very irregular in 

 outline and vaiy from 0.027 to O.OTmm. in length (Plate LXXIX, fig. 

 2(). The tentacles themselves are devoid of deposits. 



This species ma}" be ranged, in TlieeVs classitication," along with 

 cebuense^ magnum^ parvuin, occidentale ^ and vaadatniit^ which have 

 deposits of bod}' wall itself, tables, and "calcareous ring of ten simple 

 or compound pieces, always with live radial posterior bifurcate pro- 

 longations, made uj) of several separate parts or joints." The present 

 species differs from each of the above in details of calcareous ring, 

 deposits, as well as in color. Parwiin has but 18 tentacles. The disk 

 of the tables of A«y^'aMV;^.s<^ resemble somewhat ihoiio. oi Thyonidiuni 

 inflatum (Sluiter), but the latter have four upright pieces to spire, 

 and the animal itself, which is figured by Sluiter.'' has a considerably 

 different habit. On the whole, the present species appears very dis- 

 tinct from any previously descril)ed. 



THYONIDIUM ALEXANDRI, new species. 



Plate LXXIX, llg, o; Plate LXXX, tigs. .S, -^a-e. 



Tentacles 20, five pairs of large ones, alternating with five pairs of 

 extremely small ones. Body terete, tapering toward either extremity, 

 the posterior being much slendei-er than anterior and narrowed into 

 a short caudal prolongation; anterior extremity (tentacles entirely 

 retracted) truncate. Pedicels in a double series along each ambula- 

 crum of trivium, the two ventral interambulacra being entirely naked; 

 pedicels scattered all over dorsal and dorsolatei-al surface, there being 

 no regular arrangement on two dorsal radii; pedicels larger than in 

 preceding species. Body wall thick and minutely roughened with the 

 densely crowded tables. General facies remarkably like Cucwnaria. 

 Deposits: Tables similar to those of preceding species, but crown 



f'Challenger Holothurioidea, II, p. 146. 

 ^Siboga Holothurioidea, pi. ii, fig. 10. 



