282 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



mesh is a round knob, which gives rise very rarely in young indi- 

 viduals to an irregular network over the original plate, but becomes 

 inconspicuous* in old ones. Mean diameter of plates and number 

 of holes increase with age. In the largest specimen these plates may 

 measure 400/* in diameter and have 36 holes. Dorsal scales thin, 

 smooth, round in outline, lying imbricated upon one another. Ex- 

 cept those lying quite near the ventral margin, they show no con- 

 siderable differences in size, being 1.0-1.5 mm., and only rarely 2.5 

 mm., in diameter. Some of these scales may have a hole, through 

 which the dorsal pedicel is given out. Around the mouth and the 

 anus the scales are triangular in shape and show no regular arrange- 

 ment. In the largest specimen there are 27 scales between the 

 mouth and the anus and 30 in a transverse line at the widest part of 

 the body. Between the anterior margin of the sole and the mouth 

 there are 10, between the anus and the posterior margin of the sole, 

 12. Ventral pedicels have arched, elongated plates with two rows 

 of holes, and an end plate measuring 150-180// in diameter. Pedi- 

 cels of dorsum have simple supporting rods and a small end plate. 

 Supporting-rods of tentacles are similar to those of pedicels but 

 broader and have more holes. Calcareous ring consists of 10 slender 

 segments with no posterior prolongations. The ventral interradials 

 are closely pressed on to the midventral radial segment. Polian 

 vesicle and stone canal single. Genital tubes numerous and undi- 

 vided. Eespiratory trees 2, weakly developed. ■ 



In the form of the body and the arrangement of the ventrolateral 

 pedicels the present species resembles Ps. dorsipes Ludwig, but dif- 

 fers from it in the following points: First, dorsal pedicels few and 

 inconspicuous, each passing through a pore in the scale; second, 

 deposits of sole of only one kind; and, third, pedicels very few along 

 the odd ambulacrum. The specimen described by Theel as Psolus 

 sp. (?) (Blake Holothurioidea, 1886, pp. 15, 16) seems to be a young 

 of an allied species. Psolus incertus Th6el is also very near to this 

 species. 



Habitat. — South of Totomi; Sagami Sea. 



Type.— Cat. No. 34183, U.S.N.M. 



88. PSOLmiXJM BULLATUM, new species. 



Plate 11, fig. 33. 



Station 4779. One specimen. 

 Body oval in dorsal aspect, dorsum vaulted, ventrum concave. 

 Mouth and anus dorsal. Sole 12.5 mm. long and 10.5 mm. broad; 

 thickness of body, 3.5 mm.; distance from mouth to anus, 11 mm. 

 Color white all over, with rather coarse granules on the dorsal scales. 

 In external appearance the animal very much resembles Psolus 

 fabricii (Diiben and Koren). Tentacles 10, midventral pair slightly 



