222 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



diameter of 430/*, while those scattered in ventrum and pedicels 

 are smallest, the diameter reaching down to 50/1. Tentacles are 

 strengthened by bent, cylindrical rods with several short knobs 

 usually in pairs, and perforated with very minute holes at each end. 



Except that the dorsal papillae are arranged in very indistinct 

 rows, Synallactes challengeri (Theel) agrees with the present species 

 in every essential character. 



Habitat. — Hokkaido (Mitsukuri, 1912); Bering Sea; north of Sado 

 Island; west of Hokkaido; off Cape Terpyeniya, Sakhalin. 



4. SYNALLACTES MULTIVESICULATUS, new species. 

 Plate 8, figs. la-c. 



Station 5036. Three specimens. 



Station 5046 or 5047. One specimen. 



Station 5051. One specimen. 

 Body slightly flattened, more tapering posteriorly than anteriorly, 

 250 mm. long and 45 mm. broad. Mouth subventral, anus terminal. 

 Color brown, some with yellowish, others with purplish tinge, ven- 

 trum but slightly lighter. Tentacles 20, of intense brown color 

 tinged with red. Pedicels rather few but quite large, 10 mm. long 

 and 5 mm. across at base. The odd ambulacrum has two zigzag 

 rows of about 48 pedicels each; ventrolateral ambulacra each with 

 a zigzag row of 38 pedicels. Papillae are small, only 8 mm. long at 

 most, having no wartlike base. They form six rows on dorsal side, 

 each row consisting of about 45 papillae. Tablelike deposits scat- 

 tered in perisome are similar to those of S. nozawai, only differing 

 in being almost exclusively of triradiate type (pi. 8, figs. la-c). 

 They are largest near bases of papillae, with arms attaining the length 

 of 165/*, and smallest on ventrum, especially on pedicels, with arms 

 measuring only 35/*. Besides the scattered small tables, a few deli- 

 cate supporting rods are found in papillae, and the end-plate is repre- 

 sented by a number of irregularly branched rods. Unlike the 

 papillae the pedicels contain numerous, very robust rods and a single 

 end plate. Supporting rods of tentacles are similar to those of 

 papillae. Radial segments of calcareous ring have each a bifurcated, 

 prolonged anterior process. Polian vesicles are of a deep purplish- 

 black color, numbering up to 13. Even in a young specimen 30 mm. 

 long there were found 9 vesicles. Stone-canal situated in dorsal 

 mesentery. Genital tubes branched twice or thrice, forming 2 tufts. 

 Respiratory trees 2, well developed. 



Besides the difference in deposits noted above as obtaining between 

 this species and S. nozawai, the relation of size and number between 

 pedicels and papillae is reversed in the two species. S. chuni Augustin 

 ( = S. triradiata Mitsukuri) has triradiate deposits, but the arms of 

 the table are slender and slightly bent, while in the present species 

 they are thick and straight. Moreover, the pedicels are smaller and 



