comparison with one of the cotypes of O. oliveri, which I have 
received through the kindness of Mr. W. R. B. Oliver, shows, 
however, that the difference in the shape of the ventral plates is on!y 
apparent, due to the rather crude character of the said figure in 
Benham’s paper. I find the ventral plates in the cotype, from 
the Kermadec Islands, to be quite like those of my New Zealand 
specimens, as represented in Fig. 8 . 1 . 
There are a few other points to which attention should be 
called, indicating apparent differences between the New Zealand 
specimens and the typical form from the Kermadecs. Ben ham 
States the dental papillæ to be arranged in four horizontal rows of 
4 in each row, making thus 4 vertical rows. In the cotype in hånd 
the papillæ form only three vertical rows; only at the upper 
(outer) edge there are four small papillæ. This discrepancy, evid¬ 
ently, is due to the faet that the type specimen was mueh larger, 
14 mm diameter of disk, the cotype measuring only 7 mm. Other- 
wise Benham’s figure does not correspond to the description, as 
it shows 7 and 5 papillæ in a horizontal row. The New Zealand 
specimens agree with the cotype in having the papillæ in three 
vertical columns; only in the largest specimen, 8 mm diameter of 
disk, the upper papillæ are fairly distinetly arranged in four columns. 
— The small oval plate, seen along the genital slits in Benham’s 
figure, I do not find in any of the specimens in hånd; on the other 
hånd, Ben ham does not show the large genital plate bordering 
the outer extremity of the genital slits. The raised median pro- 
minence in the distal margin of the dorsal plates I do not find 
either in the cotype or in the New Zealand specimens, or, at most, 
only very indistinetly indicated. This can thus hardly be a constant 
feature. Upon the whole, I do not see any character by which it 
might be possible to distinguish the New Zealand specimens from 
those from the Kermadecs, not even as a variety. 
The variety of this species mentioned by Ben ham (Op. cit. 
p. 156')- does not appear to me to deserve this designation. Prof. 
Ben ham having kindly sent me one of the specimens I must 
say that on comparing it with the cotype and with the New Zea¬ 
land .specimens I do not see any reason for distinguishing it as a 
separate variety. The faet that the radial shields are more distinet 
