57 
To these differences come the important characters from the 
inner anatomy, borealis being viviparous and hermaphroditic (pro- 
terandric), with only one single interradial gonod at each bursa, 
while A. securigera is not viviparous and has 3—4 gonads at the 
interradial side of the bursæ and — sometimes, at least, — one 
at the adradial side (observed only in a male specimen). 
The two species are thus in reality so distinet that, on a care- 
ful examination, the identification can never be doubtful, but it 
may sometimes be necessary to dry the specimens in order to see 
the characters distinetly. 
It might seem superfluous thus to discuss the differences be- 
tween these two species, since according to the recent classific- 
ation of Ophiurids they are referred to different genera, viz. secu- 
rigera to the genus Ampbiodia Verrill, while borealis is retained 
in the genus Amphiura s. str. It is, however, by no means super¬ 
fluous to discuss their distinguishing characters, partly in view of 
the faet that they have really been confounded, partly because the 
difference between the two said genera is so very slight, consisting 
in faet only in a little difference in the mouth papillæ, Ampbiodia 
having two outer mouthpapillæ, while Amphiura s. str. has only 
one. I find, moreover, that this character is by no means constant 
in securigera , and also in borealis there are sometimes two outei 
mouth papillæ. To refer these two species to different genera for 
this sole reason seems to me quite unreasonable, the two species 
being otherwise so closely alike that there can be no doubt, they 
are really nearly related. In faet, I think Sars is quite right in re- 
garding them as related to Amphiura filiformis which has the 
same peculiar axeshaped armspine, though not so strongly devel- 
oped. In case these species should be separated from Amphiura 
s. str. the old name Ophiopeltis Dub. Kor. would have to be used 
for them, not the name Ampbiodia Verril. But I do not think 
there is sufficient reason for a generic distinetion. 
It is funny to see that Bell in his Catalogue of British Echi- 
noderms (p. 121) declares A. securigera „allied to A. squamata , 
perhaps only a variety of it“. Even if he has not seen a spec¬ 
imen of securigera, the merest glance at the figures given by 
Duben & Koren (which he quotes) ought to have shown him 
that these forms have nothing with one another to do. 
