no. 2073. H0L0THURIAN8 FROM NORTHWEST PACIFIC— OHSHIMA. 271 



once or twice, ending in two diverging spines. Between them are 

 found very rarely modified tables with. 4-armed base, up to 160 ji in 

 diameter. Pedicels thorny in appearance, owing to the presence of 

 numerous, long-spined buttons (figs. 24c, d). End plate small and 

 rudimentary, with irregular contour. In the introvert are found 

 complicated rosettes, oval in outline, 40/* long. Supporting rods of 

 tentacles are characteristic and are of two principal forms. The 

 slender, distal branches are supported by slender, smooth rods with 

 some holes at each extremity, while in the thick, proximal parts, some 

 are quite rod-like, but others are derived from complicated rosettes, 

 resembling those found in Echinocucumis adversaria Semper. 1 There 

 are all sorts of transitional forms between them. Calcareous ring 

 resembles that of Th. multipes, but is more slender. Polian vesicle 

 and stone-canal single. Retractors inserted at one-fourth the body 

 length from the contracted anterior end. Respiratory trees well 

 developed; genital tubes unbranched, numerous and slender. 



In spite of its close resemblance to Th. multipes in external features 

 the present species is characterized by the forms of its deposits in gen- 

 eral perisome and tentacles. Th. fusus (Miiller) and Th. serratus 

 Britten differ from it in the shape of the buttons and end plate. 



Habitat. — Suruga Bay. 



Type.— Cut. No. 34173, U.S.N.M. 



74. THYONE IMBRICATA, new species. 



Station 5023. Four specimens. 

 Body a short spindle in shape, with mouth and anus directed 

 dorsad. Length, as measured along ventral side, 34 mm.; along 

 dorsal, 14 mm. ; diameter, 8 mm. Color pure white from the presence 

 of scale-like deposits which stiffen the integument. Tentacles 10, 

 midventral pair being a little smaller than the rest. Pedicels uni- 

 formly scattered all over the body. Scale-like deposits are irregu- 

 larly oval, with uneven margin, rather thick and complexly latticed; 

 diameter, 0.3-1.2 mm. They are imbricating, but leave here and 

 there narrow interspaces through which the pedicels pass outwards. 

 Near the free margin of each scale stands a short, conical, spinous pro- 

 cess projecting obliquely on the body surface, and measuring about 

 0.45 mm. in length. In the introvert are found scattered, elongated 

 plates with holes and knobs, measuring 0.16-0.4 mm. in length. 

 Pedicels supported by small rods with few holes; an irregular end 

 plate, 0.10-0.17 mm. in diameter, is present. Tentacles richly sup- 

 plied with supporting rods in the form of curved plates, 0.13-0.26 mm. 

 in length. Calcareous ring well developed, with the posterior margin 

 deeply indented but destitute of tail-like prolongations. Retractors 



i See Ludwlg, Vettor Pisani Holothurieti, 1887, p. 24, pi. 1, fig. 3D. 



