272 
well possible that the adult specimens of the two forms may be 
recognizably distinet. 
In my opinion, it is the safest course for the present, to keep 
the New Zealand form as a separate species, duly pointing out its 
close relationship and possible identity with A, imbellis. To the 
Australian species A. pectincitus it appears to be not so nearly related. 
3. Astvopecten pvimigenius n. sp. 
PI. XII. Figs. 1-2. 
N. of Cuvier Isl., 30 fms. 2 specimens. (Captain Bol Ions). 
R—28 mm; r. 9 mm; R = 3 r; breadth of ray at base 10 mm; number 
of superomarginals 17. 
R 16 mm; r. 6 mm; R = 2.7 r; breadth of ray at base 7 mm; number 
of superomarginals 13. 
Paxillar area rather narrow, occupying only half the width of 
the arm; the paxillæ are arranged in distinet transverse rows on 
the arms, two rows corresponding to one marginal plate; they are 
very low, hardly with any pedicel at all, on the disk very crowded 
and scarcely decreasing in size towards the middle of the disk, 
where no elevated cone is found. There are about 6—8 central 
spinelets and an outer circle of about 12, all in the shape of short, 
smooth grains (Fig. 3). 
Superomarginals very broad and low, making a very broad mar¬ 
gin to the ray, which is upon the whole low and flattened. No 
spines on the superomarginals, only a uniform, close covering of 
low, rounded grains. Inferomarginals (Fig. 2.a) with an oblique 
series of 6 pointed, closeset, appressed spines. The middle ones 
are the longest, about so long as the width of the plate only. These 
spines, accordingly, are very little prominent and hardly to be seen 
from above. Sometimes there is a small spine adorally to the 
upper one, the series then consisting of in all seven spines. Fur- 
ther there is another parallel series of 3—4 similar, slightly smaller 
spines on the upper, aboral edge of the plate, covered bv the spines 
of the primary series and distinetly seen only on the removal of these 
latter. A series of 4—3 lateral spines is found along the aboral 
edge of the plate, somewhat smaller than those of the oblique 
series, likewise closely appressed. Otherwise the inferomarginal 
