REPORT ON THE CRINOIDEA. 363 . 
farther out on the arms are smaller than the corresponding pinnules of Metacrinus 
costatus ; while the lowest pinnules are smaller, smoother, and have more rounded joints 
than the more massive but flattened pinnules of Metacrinus costatus with their serrate 
ends. On the other hand, the expansion of the two basal joints in the pinnules beyond 
the palmar axillary is more conspicuous in Metacrinus wyvillii than in Metacrinus 
costatus, and the remaining pinnule-joints are distinctly stouter than in that species. 
There is a great amount of difference between the two specimens described above 
except in the characters of the stem, which are extremely constant, the number of 
internodal joints beg almost invariably seven or eight. In the first place the basal 
plates of one individual are entirely absent; and each of the radials, which are slightly 
higher than in the other example, has a small downward projection in the middle of its 
base which rests directly on the top of one of the five ridges of the stem, as shown in 
Pl. XLIX. fig. 2. The basals of the other example are smaller than is usually the case 
in the genus; but their total absence, at any rate on the exterior of the calyx, 1s a most 
singular anomaly. One result of it is that the position of the cirri is interradial and not 
radial, as is generally the case; and presumably therefore the peripheral vessels from 
which the cirrus-vessels are supplied have a similar position. But these peripheral 
vessels are continuous above with the chambers of the chambered organ, which are 
normally set in the direction of the rays (Pl. XXIV. figs. 5-8; Pl. LVIII. figs. 1, 2; 
Pl. LXII.—ch) ; while the primary axial cords of the rays start from the interradial angles 
of the chambered organ (Pl. XXIV. fig. 7; Pl. LVILL. figs. 1,3; Pl. LXII.—az). If the 
mutual relation of these organs in this anomalous specimen were only known it would 
very probably throw much light upon the structure of the lower part of the calyx in 
those Paleeocrinoids which have interradial cirri, such as Heterocrinus, Locrinus, Bary- 
crinus, and Belemnocrinus florifer. It is of course possible that the basals may be 
internal and concealed as in most Comatule and in some varieties of Hnerinus; but I 
cannot help thinking that if they were really present at all the cirri would be placed 
radially as they usually are, and not interradially as is actually the case. 
This baseless’ specimen presents the only irregularity in the number of the radials 
which occurs in the two individuals. The second radial is not traversed by a syzygy, as 
is invariably the case in all the other rays, though the second syzygy is in its normal 
position between the fifth and sixth joints of the primitive ray as in the ordinary type ; 
but there is no additional joint between this syzygy and the axillary, so that the ray 
consists of six joints with the fifth a syzyey. 
All the ten primary arms of this individual, however, consist of six joints, of which 
the third is traversed by a syzygy; while in the other specimen with a more normal 
calyx there is only one distichal series of this character, together with one of eight 
joints, of which the second is a syzygy; and the remaining six also consist of eight joints, 
but have a syzygy in the third. The later arm-divisions of the baseless specimen are 
