146 HOLOTHITRIID.\E. 



more conspicuous on ventral surface; there are two well-marked series in each 

 of the three ventral ambulacra. In each of the dorsal ambulacra is a double 

 row of conical papillae. Tentacles twenty, rather small. Calcareous ring very 

 well developed; interradial pieces wider than high with a conspicuous anterior 

 point; radial pieces much larger with a strongly concave posterior margin 

 and two conspicuous, truncate anterior projections. No ampullae on the 

 tentacles. Respiratory trees well developed. Genital glands in two tufts, 

 one on each side of the dorsal mesentery. Anus terminal and not sunken in 

 a vertical furrow. 



Calcareous particles, crowded tables with simple spires (Plate 4, fig. 14) 

 of three rods united by three cross-bars but with the points free, straight and 

 parallel; disks triradiate, in the typical condition (Plate 4, fig. 15) with three 

 large oval perforations and a second series of three somewhat smaller holes 

 alternating with them; usually, however, a third, often a fourth and not rarely 

 a fifth scries of perforations is present (fig. 16) ; diameter of disk 150-500 ^, 

 but usually 250-400; height of spire equals disk-diameter or somewhat less. 

 In many of the larger tables, the primary perforations are never closed in dis- 

 tally, so the disk remains a triradiate plate (Plate 4, fig. 17), with the outer end 

 of each bar dichotomously branched and the final expansion perforated with 

 1-4 holes. 



Station 4642. Galapagos Islands: Hood Island, 4 miles southeast of Ripple Point. 300 fms. Bott. 

 temp. 48.6°. Brk. sh., glob. 



One specimen. 



This species is notable for the relatively shallow water in which it lives and 

 the high bottom temperature of its habitat. It is closely related to several of 

 the recently described Japanese species of Sj-nallactes, particularly to discoidalis 

 Mitsukuri. It differs from this form, however, in having fewer papillae and 

 pedicels; four rows of papillae instead of six, and only two series of midventral 

 pedicels instead of four to six. The tables are larger than in discoidalis, in 

 which species the disk is only about 175 ix across, and the spu-e is quite different, 

 as the three rods composing it are more or less fused in the Japanese species. 



Pseudostichopiis mollis. 

 Th£el, 1886. Chauuengek Hoi., pt. 2, p. 169. 



These specimens are 20-125 mm. in length and show the usual diversity 

 of this species in the condition of the body-wall and its surface. Some are firm, 



