544 " THETIS " SCIENTIFIC RESULTS. 



hardly visible. Under arm-plates more or less pentagonal ; 

 first one much longer than wide, narrowest proximall y; succeeding 

 wider than long, distinctly separated from each other. Side arm- 

 plates large, meeting both above and below ; each one carries a 

 conspicuous vertical ridge, bearing five or six sharp, rather stout, 

 smooth arm-spines; lowest spine longest, exceeding a joint ; upper- 

 most spine shortest, about half as long as lowest. Tentacle-scales 

 long and sharp, very conspicuous ; the second pore has three, the 

 third two or three, the fourth two or one, the fifth and all 

 succeeding pores one. Colour, very light brown. 



1 specimen from Station 57. Off Wata Mooli, 54-59 fathoms ; 

 all mud. 



This specimen is so small and in such poor condition, I have 

 hesitated to base a new species upon it. But there seems to be 

 no question that it belongs in Verrill's genus Ophiopristis, and I 

 do not find any species of that group to which the specimen could 

 possibly be assigned. 



OPHIOTHRIX ACESTRA,2 6 sp. nov. 



(Plate liii, figs. 4-5). 



Diameter of disc, 7'5 mm.; length of arm, 24 (?) mm. Disc 

 somewhat puffed in interbrachial areas, but not conspicuously 

 so, covered with erect, slender stumps, which are crowned with 

 three or four (rarely five) long, slender, acute, diverging spinelets; 

 these spinelets are more than half as long as the stump. Many of 

 the stumps, particularly at centre of disc, are prolonged into very 

 slender, needle-like spines, three times as long as the ordinary 

 stumps ; these acicular spines are not smooth, but carry at least, 

 near middle and below, three or four irregularly scattered, coarse, 

 sharp teeth. Eadial shields broadly tringular, more or less 

 separated by a narrow series of stump-bearing plates, and more 

 or less concealed by the thorny stumps, which are borne to some 

 extent by the radial shields themselves ; outer ends of radial 

 shields usually bare and well-defined. Upper arm-plates some- 

 what keeled, trapezoidal, but overlapping so as to appear pent- 

 agonal, with a very short proximal side ; two distal sides longer 

 than two proximal ; distal angle rounded. Interbrachial spaces 

 below bare, except at centre and margin, where thestvimp-bearing 

 plates on the disc are continued ; when dry, the supplemental 

 genital plates, next to oral shield, and the genital plates them- 

 rselves, become very conspicuous. Oral shields wider than long, 



~® aKe(rTpa = a. darning needle, in reference to the long needle-like spines 

 on disc. 



