REPORT ON THE CRINOIDEA. 327 



radials ; but this is not quite the case in the original of fig. 2 on PI. 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 

 toyville-iliomsovi and the other semi-free types. 



The young individuals of Pentacrinus naresianus, besides exhibiting the usual 

 characters common to all young Pentacrinidse {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 (PI. XXXa. 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 nrm-syzygies are also slightly diff'erent 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 PI. XXXa., wdiich 

 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 growth. 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, wdiich is segmented in the same way as the stem, and is continued do\vn- 

 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 cii-rus-sockets on to the infra-nodal joints, so that no tra(;e of them is visible. 



1 The absent cirri at this node were erroneously inserted 1iy the artist, when restoring the broken ones elsewhere ; 

 and I did not notiee the fact till it was unfortunately too late to remedy it. 



