RECENT OPHIURANS. 2lS 



387. 0. PLESIOTAXIS, sp. nov. (irXi/irfc, near, close + tAJis, row, series). Plate 3, f. 9, 10. 



Disk, 16 mm. in diameter; arms all broken, but probably about 120 mm. 

 long. Disk covered by radial shields and scales; the largest of the latter are 

 at the outer corners of the radial shields; about 25 of the scales carry prickly, 

 cylindrical, spinelets; along the margins of nearly all scales and even between 

 and at outer margin of radial shields are numerous, very small rough, conical 

 spinelets or pointed granules. Radial shields large, bare, smooth, and closely 

 joined. Upper arm-plates shghtly swollen, rough, with minute, sharp granules, 

 broader than long, with a gentle curve distally and a deep curve proximally; 

 all well-separated from each other. Interbrachial spaces below covered with 

 scales and scattered, rough conical spinelets or granules. Oral shields very 

 small, warty, and rough. Adoral plates relatively very large, somewhat pentag- 

 onal. Both oral shields and adoral plates bear more or fewer rough spinules, 

 much Uke the oral papillae but more thorny; these spinules tend to form a 

 cluster at the inner point of the oral shield, where the adoral plates meet. Oral 

 papillae and tooth-papiUae very numerous, spiniform, Uttle if at all flattened; 

 they nearly conceal the oral plates. First under arm-plate small and difficult 

 to make out; succeeding plates wider than long and rapidly becoming three 

 times as wide as long; median distal portion swollen and very rough; lateral 

 portions also quite rough. Side arm-plates large, meeting broadly below and 

 less broadly above; each carries a series of 9-10 minutely roughened spines, of 

 which the second or third (from above) is longest and rather exceeds two joints, 

 while the two lowest are very small and rough; the series are closely approxi- 

 mated on the first two joints beyond disk (hence the name). Tentacle-scales on 

 first arm-pores, 3-4, very big, flat, and conspicuous; the free end is very broad, 

 wider than one half the length of the scale; succeeding scales gradually becom- 

 ing smaller, fewer, and rougher; at middle of arm there is only a single scale at 

 each pore and it is very minute and rough; the pore itself is exceedingly hard 

 to make out. Color, pale wood-brown. 



HoLOTYPE (M. C. Z. 3543). Andaman Islands, 220-240 fms. Investi- 

 gator collection. 



This specimen is one of those identified by Koehler (1897, Ann. sci. nat. 

 ZooL, ser. 8, 4, p. 360) as fasciculata, but in my opinion, it is not that species. 

 I have compared it with typical specimens of fasciculata, hystrix, polyploca, 

 rugosa, and vitrea, and it seems nearest the last. It differs from all the West 

 Indian species in the approximation of the basal series of arm-spines. It is 

 different from fasciculata further in the roughness of the disk-spinules, in the 



