REPORT ON THE CRINOIDEA. 363 



farther out on the arms are smaller than tlie corresponding pinnules of Metacrimis 

 costatus ; while the lowest pinnules are smaller, smoother, and have more rounded joints 

 than the more massive but flattened pinnules of Mctacrinus 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 wyvUlii than in Mctacrinus 

 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 being 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 

 PI. 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, is 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 chaml)ers 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 LVIII. figs. 1, -3 ; PL LXU.—al). If the 

 mutual relation of these organs in this anomalous specimen were only kuowTi it would 

 very probably throw much Hght upon the structure of the lower j)art of the calyx in 

 those Palseocrinoids which have interradial cirri, such as Heterocrinus, locrinus, Bary- 

 crinus, and Belemnocrimis Jlorifer. It is of course possible that the basals may be 

 internal and concealed as in most Comatulse and in some varieties of Encrinus; 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 I'adial is not traversed by a syzj^gy, 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 t}"pe ; 

 but there is no additional joint between this syzygy and the axillary, so that the ray 

 consists of six joints with the fifth a syzygy. 



All the ten primary arms of this indi\ddual, 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 \vith 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 thiixl. The later arm-divisions of the baseless specimen are 



