REPORT ON THE CRINOIDEA. 251 
in ihrer urspriinglichen Gestalt verinderte Basalia.” 
He supposed these basals to be in 
a more embryonic condition than those forming the rosette of Comatula, and still 
remaining independent of one another as five 
isolated plates. But if this be the case one 
would surely expect to find the basals 
below the radials, and separating them from 
the top stem-joint as in the early stages of 
the Pentacrinoid larva of Comatulee and in 
the Stalked Crinoids generally. 
Ludwig, however, represents the supposed 
basals both in horizontal and in vertical 
sections as occupying a position above the 
radials, and forming the floor of the body- 
cavity some way above the chambered organ, 
with which the basals of Crinoids are always 
closely related. The position assigned by 
him to the basals of Rhizocrinus is one which 
I have no hesitation in describing as utterly 
impossible for these plates to occupy; and 
the dotted line inserted in his longitudinal 
section to mark the junction of the supposed 
basals with the first radials below them is 
purely imaginary. The same may be said 
of the lines that indicate an enveloping of 
the radials by upward processes of the 
supposed top stem-segment below them, 
which would cut off the radials altogether 
from the exterior of the calyx (compare wood- 
cut, fig. 17). That part of the calyx of Rhizo- 
erinus Which was considered by Ludwig to 
represent the embryonic basals altered in 
position, though not in nature, really belongs 
to the radials as was figured by Sars,’ who 
spoke of these plates as follows :—“étant 
tronquées dans leur partie intérieure, elles 
Fic. 17.—Diagrammatie vertical section through the calyx and 
disk of Rhizocrinus lofotensis ; x 75. Altered from Ludwig. 
The section is represented as passing through the middle line of 
aray on the left hand side, and as almost (but not quite) inter- 
radial on the right. A, axial cord of ray; a, primary inter- 
radial cord; B, basal tube; 0,, first brachial ; br, central 
calcareous plug, the basal rosette of Sars ; ca, fibrillar sheath 
round vascular axis of stem; ch, chambers of the quinque- 
locular organ ; ch’ their downward extension into the stem; 
c.co., portion of circular commissure formed by the secondary 
interradial cords ; fg, fore-gut ; G, mid-gut ; /, basiradial liga- 
ment; m, muscle; 7, oral ring of the ambulacral nervous 
system ; O, oral plate; Ry, radial ; re, rectum; st, top stem- 
joint ; T, tentacle ; v, central vessel of stem ; w, radial water- 
vessel ; wr, water-vascular ring ; x, plexiform gland. 
forment réunies un large anneau en laissant entre elles au milieu un espace arrondi 
ou un peu pentagone, rempli par la plaque ‘en rosette’ (fig. 42, 43, 7) mentionnée plus 
haut, reste probable des basales. 
Au point ot cette plaque rencontre le bout tronqué 
1 Crinoides vivants, p. 14. 
