242 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 48. 



there may be a branch (figs. 11a, b), never symmetrically triradiate. 

 They are very sparsely scattered in general perisome, tentacles, pedi- 

 cels, radial muscles, peritoneum, and genital organ. In general peri- 

 some they vary in length between 100 and 280/*, but are most com- 

 monly 150-170;*. In dorsum they are more sparse and slender. In 

 tentacles, papilla?, and pedicels the rods are of a similar shape, but 

 larger, 200-300//, and more numerous. No end-plate in pedicels. 

 Spicules in genital tabes and duct are numerous, delicate, usually 

 branched, and spinose (fig. 11a), 120-240/* in length. The walls of 

 intestine, cloaca, and stone-canal are destitute of deposits. Calca- 

 reous ring consists of 5 radials only, which have 6 pairs of simple 

 or only bifurcated processes. Stone-canal minute, meandering in 

 course, opening midway between anterior end and dorsal skin fold. 

 Polian vesicle single. Genital tubes short, once or twice branched, 

 forming some 15 tufts attached to a long, wide genital duct, measuring 

 over 100 mm. in length and 5 mm. in diameter. Mesentery repre- 

 sented by a number of ribbonlike filaments, 1-1.5 mm. in width. 

 Cloaca provided with an inconspicuous coecum. Radial muscles 

 thick, dorsal pair 9 mm. wide and divided, the others not. The mid- 

 ventral one is markedly slender in the anterior half. 



From the two hitherto known species of the genus, A. ecalcarea 

 (Theel) and A. lactea Theel, the present species differs in having no 

 symmetrical triradiate deposits. 



Habitat. — Off Kii; south of Totomi, Honshu. 



Type.— Cat. No. 34158, U.S.N.M. 



Genus SCOTOPLANES Theel. 



33. SCOTOPLANES THEELI, new species. 



Station 5032. Six specimens. 



Station 5033. Three specimens. 

 Body ovate, posterior half broader than the anterior. Length 

 80 mm., width 30 mm., the latter never exceeding one-half of the 

 former. Dorsum vaulted, ventrum flat, mouth and anus terminal 

 but directed ventrad. Color light brownish-gray all over; integu- 

 ment very thin and soft. Tentacles 10, terminal disk with 10 mar- 

 ginal digits and a number of knob-like processes in the central part. 

 Pedicels 7, rarely 6, forming a row along the whole length on each 

 side of ventrum; they decrease in size from the anteriormost ones, 

 which measure 15 mm. long and 7 mm. across at base, backward, 

 the last one being often quite rudimentary. Dorsal papillae invaria- 

 bly in 3 pairs, the first being situated at about the middle of the 

 anterior half of body, the second, at the middle of body or more 

 commonly a little more anteriorly. Both these pairs are long, meas- 

 uring 23 mm., and 4 mm. across at base. The third pair stand imme- 

 diately behind the second but are slightly more lateral in position, 



