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the following observations. The marginal spines of the jaws are 
fairly constantly 2 large inner ones on each half and 3—4 distinctly 
smaller ones outside these. Each half of jaw carries, about on its 
middle, a large and conspicuous, somewhat outwards curved spine, 
the two spines of the jaw forming together like a pair of horns. 
Rarely there are two such spines on each half of jaw, placed side 
by side. The furrow spines are generally three on a few of the 
inner adambulacral plates, two on those beyond ; as a rule they are 
unequally developed, the outer one being the larger. The first pair 
of adambulacral plates (very rarely also the second pair) may carry 
two outer spines instead of one. The interradial plates of the oral 
side may be said to carry, as a rule, only one, strong spine; but 
not rarely those near the margin carry each two spines, and this 
may continue so far inwards as unto about the middle of the area. 
Sometimes also a few of the inner plates may carry two spines. 
Also the spines on the disk plates may vary not inconsiderably; 
they have, generally, distinctly the shape of short, more or less 
thorny, closeset spines, but sometimes they are coarse, rounded 
grains. As a rule the arms are quite distinet, but specimens may 
be found which are regularly pentagonal. The difference in outline 
is, however, for the greater part due to the faet that the inter¬ 
radial edge may bend inwards to a various degree on preservation. 
Farquhar (Op. cit. 1897) has pointed out that this species is 
subject to considerable variation, and that several of these varying 
specimens “are so distinet from normal specimens of A. reguluriSy 
that if a series were found in a separate locality, a new species 
might safely be established for them”. Among the specimens in 
hånd there are two forms which I should, indeed, be very mueh 
inelined to regard as separate species. As I have, however, only 
little material thereof, I do not feel satisfied that they are really 
distinet species and therefore shall prefer to designate them only 
as varieties of Å. regulariSy leaving it to future researches to 
decide, whether they deserve to rank as separate species. In any 
case they appear to me so different from the typical form that it 
is unjustifiable simply to identify them as A. regularis. 
Variety a. (PI. XII. Fig. 17). Two specimens from Wellington, 
sent me by Mr. Farquhar 1911, together with some specimens 
of the typical form. The diameter is 25—26 mm. They are perfeetly 
