156 
is another question; but here, again, I am inclined to think so, 
in spite of the differences which can be pointed out. The faet that 
H. L. Clark, who had a cotype of Lyman’s Ophioenida pilosa 
for comparison with his specimens, does not hesitate in declaring 
them identical, makes me the more confident that both the New 
Zealand and the N. S. Wales form really belong to this species. 
As appears from the figures given here, the specimens differ 
so considerably according to age that, if they had not been taken 
all together in the same haul, one would hardly think of regarding 
them as belonging to one and the same species. It is mainly the 
shape of the ventral plates which differs so conspieuously. In a 
specimen of 4 mm diameter of disk (Fig. 27.?) they are narrow, 
elongate, distinetly longer than broad, the basal part being some- 
what broader than the outer part. In a specimen of 7 mm dia¬ 
meter of disk they have mainly the same character in the prox- 
imal part of the arm, but farther out they get a very character- 
istic polygonal shape, narrowing in their outer part (Fig. 27 . 1 , 3 ); finally 
in the largest specimen, 11 mm diameter of disk, they are almost 
regularly rectangular, distinetly broader than long (Fig. 27.5). The 
same transformation of the ventral plates according to age is to be 
observed in the N. S. Wales specimens. The difference in the shape 
of the dorsal plates in smaller and larger specimens, as shown by 
figs. 27.8 and 4, though no less striking, is not so surprising. It may 
be pointed out that generally the first complete dorsal plate is 
rhomboidal. 
The armspines are in the larger specimens 7—9 in the prox- 
imal part of the arm; in the smaller specimens there are only five, 
as in the type. They are more or less distinetly flattened, some- 
times slightly widened and dentate at the point (Fig. 27.3-4), but 
this is no constant feature. Generally the lowermost one is the 
longest, and sometimes also the upper one or two arc somewhat 
longer than the middle ones; but, again, this is not constantly so. 
The radial shields are generally contiguous in the outer part, but 
sometimes they are wholly separate (Fig. 27.^). The mouth shields 
are very variable in shape, as is also the case in the specimens 
from off the N. S. Wales coast (Fig. 27. 1, e, 9—10); the form of 
mouth shields seen in Fig. 27 .1 I have, however, not observed in 
any of the specimens from off the N. S. Wales coast. 
