than long; the two inner ones are in contact, the second one hav¬ 
ing the inner edge truncated; the third almost reaches the second, 
but from the fourth they are widely separated. The inner ones 
have a convex outer edge, from the fourth the outer edge has a 
reentering curve. which gradually becomes more marked farther 
out. In the outer part of the arm the ventral plates are about 
regularly heptagonal. There is a single, rather large, smooth tent- 
acle scale. The dorsal plates are very small, triangular, with a slightly 
arched outer edge, widely separated throughout the whole length 
of the arm. The side armplates are rather prominent, carrying 7—8 
long, siender, very finely serrate armspines; farther out there are 
only 6 spines. On the proximal joints the spines may almost join 
in the dorsal middle line. 
None of the specimens exceed a size of 4 mm diameter of 
disk. The arms are broken, but apparently they are only ca. 4—5 
times so long as the diameter of disk. The colour appears to be 
that usual in Ophiacantha’s, a light yellowish-brown. 
This species, the first Ophiacantha recorded from the New Zea¬ 
land seas, is very closely related to Ophiacantha pentagona Koehler, 
a species widely distributed over the Indo Pacific Ocean. It differs 
from that species in the shape of the stumps covering the disk, 
these being provided with much longer thorns in O. pentagona (cf. 
PI. IV. Fig. 29 of Koehler’s Report on the “Investigator“ Oph- 
iuroidea and PI. 93.5 of the Philippine Ophiurans) ;^) also the tent- 
acle scale appears to be distinctly smaller in O. pentagona; the 
shape of the buccal shield is slightly different, and there are only 
5 — 6 armspines in O. pentagona. 
Also to another species it bears a very close resemblance — 
I rather think still doser than to O. pentagona —, viz. to O. adi- 
aphora H. L. Clark, from the North Pacific, the main difference 
from that species being found in the shape of the mouth shield. 
A character which might look rather essential is the shortness of 
the genital slits in O. adiaphora, where they appear not to reach be- 
yond the first armjoint, while in O. vilis they reach almost to the 
edge of the disc. I cannot, however, ascribe any greater signific- 
R. Koehler. Ophiurans of the Philippine seas and adjacent waters. 
Buil. N. S. Nat. Mus 100. 1922. 
