NO. 1555. HA WA II A N IIOLOTHURIANS— FISHER. 715 



base of tentacles, form of calcareous ring. Alexandrl l>elongs to the 

 same section of the genus as the preceding- species and is ver}" distinct 

 from any known form. The distribution of pedicels is uiuisual for 

 this genus. The specimen is evidently adult, l)ecause the gonad is 

 very large. 



This species is named for Mr. A. B. Alexander, of the Bureau of 

 Fisheries, fisheries expert during the Hawaiian cruise. To his effective 

 cooperation in that region of difficult dredging much of the success of 

 the undertaking was undoul)tedly due. 



Stil^fairiiljr PSOLHSTvE R. Feri-iev. 



Psolin^ R. Perriek, Holdtlinries, Expeil. du Travailleiir iH, <lu Tali.sinaii, 1903, 

 pp. 493, 512. 



Genus PSOLUS Okeii. 



Psolus Okes, Lehrlmch der Natnr<ieschielite, Pt. 3, Zonl., isifi, p. 352. 



Tentacles, 10; ventral surface flat, with two or three rows of pedi- 

 cels, the median radius often without them; dorsal surface convex, 

 without ambulacral appendages, usually with large calcareous scales 

 or external plates; mouth and anus sometimes with distinct valvular 

 plates; edge of bod}- sharp. 



PSOLUS MACROLEPIS, new species. 

 Plate LXXIX, figs. 1, la-/". 



Tentacles 10, rather small, arborescent. Body broadlv oval, much 

 depressed. Dorsal scales not numerous, but large, only slightly 

 imbricating, the edges, however, very tightly lifted together; lateral 

 scales decreasingly smaller, those surrounding rim rather minute; 

 only two rows of scales between mouth and anus, the middorsal 

 region being occupied by about four scales larger than the rest. 

 Mouth surrounded by five regular triangular valves, the sides of 

 which are subequal, and the bases defining a rude circle; a small 

 triangular scale between adjacent oral valves at their base; this is 

 absent between two scales. Anal aperture surrounded b}^ about 

 twelve scales, five of which are shorter and broader than others (see 

 figure). Surface of all scales except minute ones about rim of body 

 beset with irregularly spaced, small granules, which are rather sparse 

 on mouth and mediodorsal scales, and nearly lacking on anal. Sole 

 flat; median ambulacrum wholly without pedicels; the lateral ambu- 

 lacra with two series of pedicels, of which the outer are smaller, 

 rather more numerous and situated close to sharp edge of body. 

 Deposits: In ventral perisome perforated plates of irregular shape, 

 either smooth or provided with a few knobs, the perforations from 

 four to twent}' in number; in pedicels a terminal plate and numerous 

 elongated, perforated, mostly smooth rod-like plates with undulating. 



