o 
135 
As appears from a comparison of the figures of this species 
with those of A. magellanica, it is really difficult to indicate reliable 
distinguishing features in the characters of the plates or spines. 
The oral shields have the same rounded shape in both forms; the 
ventral plates are more rounded at the outer edge in spinipes, 
more straight or even slightly concave in magellanica — but, al- 
though it may appear distinet enough in the figures, the difference 
is really very slight. The single tentacle scale quite alike in both 
Fig. 16. Amphiura spinipes Mrtsn. — a. Part of oral side; b. of dorsal side; c. two 
armjoints from middle of arm, dorsal side. 
species. The dorsal plates in the interior part of the arm are some- 
what narrower and more elongated in spinipes than in magellanica; 
those further out on the arm very nearly of the same shape in 
both species. The radial shields are narrower and more elongated 
than in magellanica, ca. V 2 the disk radius, and the scales cover- 
ing the disk on both sides are distinetly finer in spinipes than in 
magellanica. The armspines are as in magellanica, 6 (more rarely 
7) at the armbase, 5 farther out, and the ventral is very mueh 
elongated, somewhat curved, and directed straight downwards. The 
tube feet are not papillose. 
Upon the whole, these two forms agree so closely that one 
might. be more inelined to think the form, here distinguished as 
Amph. spinipes, merely to represent a more siender variety of ma¬ 
gellanica. That it is, however, really a distinet species is proved 
