REPORT ON THE CRINOIDEA. 327 
radials ; but this is not quite the case in the original of fig. 2 on Pl. XXIX., for the 
basals form a compact ring entirely separating the radials from the top of the stem. 
In other specimens, again, some of the basals meet their fellows, while the remainder 
are more or less completely separated by the downward extending radials. 
Pentacrinus naresianus does not appear to be one of those which live in a semi- 
free condition like the three last described, while the stem grows to a greater length 
than in most of these forms. It is broken below in all the specimens obtained, and 
though this has sometimes taken place at a node, the fracture is evidently a recent 
one, the syzygial surface not being worn and more or less rounded, as in Pentacrinus 
wyville-thomsoni and the other semi-free types. 
The young individuals of Pentacrinus naresianus, besides exhibiting the usual 
characters common to all young Pentacrinide (ante, pp. 289-291), have one or two 
peculiarities of their own. The second radials are less closely united, only meeting one 
another for half the length of their sides (Pl. XX Xa. fig. 1); while the sides of the 
axillaries and of the two following joints are not so much flattened as in the adult, but 
the edges where the ventral and dorsal surfaces meet are sharp and straight. 
The characters of the arm-syzygies are also slightly different from those which 
appear in the adult. The backward projection of the epizygal is much nearer the edge 
of the joint than in the adult arm, in which the crest of the ridge on the syzygial face 
crosses the axial canal. This gives an entirely different appearance to the joints when 
seen in profile, as will be evident upon a comparison of figs. 9-12 on Pl. XXXa., which 
represent a young and an old syzygial pair, as seen from the side and from above 
respectively. 
The difference in the sculpture on the young and on the older stem-joints is also 
shown in Pl. XXXa. figs. 2, 3, 7. In the young individual figured on the same plate 
the head is but 55 mm. long, and there are only about fifty joints in the arms. The 
diameter of the stem is 2 mm. Its internodes are exceptionally long, seventeen or 
eighteen joints; and there are only two cirri at one of the nodes (the fifth),’ just as is 
apparently the case through the whole stem of Pentacrinus didactylus. 
Two stem-fragments from this Station (170), one of which (and possibly both) 
belong to this same individual, exhibit some remarkable peculiarities of erowth. In the 
upper one (Pl. XXXa. fig. 5) two of the nodal joints are slightly enlarged as described 
above. But seven joints lower down a kind of calcareous sheath appears on the outside 
of the stem, which is segmented in the same way as the stem, and is continued down- 
wards over the next node. This is of an altogether abnormal character. The outer 
crust shows various irregular lines, and seems to have filled up the downward extensions 
of the cirrus-sockets on to the infra-nodal joints, so that no trace of them is visible. 
1 The absent cirri at this node were erroneously inserted by the artist, when restoring the broken ones elsewhere ; 
and I did not notice the fact till it was unfortunately too late to remedy it. 
