REPORT ON THE CRINOIDEA. 37 
basals of Bathycrinus is extremely close, and in old individuals no sutures are visible 
externally (Pl. VII. figs. 1, 2, 11; Pl. VIIa. figs. 12-14), though they appear in 
transverse section (Pl. VIIb. fig. 2) and also in young examples. I have never suc- 
ceeded, however, in separating the plates from one another by the usual methods. 
The radials of Bathycrinus, on the other hand, are much less closely united. They 
are thin plates in contact with one another by quite narrow sides (Pl. VIL. figs. 6, 6a). 
Those of Bathycrinus aldrichianus were described by Sir Wyville Thomson as being 
“ often free ; but in old examples they also are frequently anchylosed into a funnel-shaped 
piece.” All the specimens which I have examined are in the latter condition, though 
the plates are readily separable. But I do not think it possible that they could ever 
be perfectly free as the other two radials are; and I have always found them to be 
closely united by ligaments up to the level of the circular commissure (Pl. VIIb. fig. 4,7), 
though they become much more free near the top of the calyx (Pl. VIIb. fig. 5). The 
Fic. 1.—Pronachocrinus kerguelensis. Calyx, x 6. 
A. Side view, showing the alternation of the five primary radials with the five others, which are separated from the centro- 
dorsal by the rays of the basal star. B. Upper view, showing the interior of the central funnel formed by the radials. 
difference between the “free” and the “anchylosed” conditions is probably only due to 
variations in the extent to which limestone is deposited around the fibres of the above 
mentioned interradial ligaments. 
The difference between the basal and radial rings in the amount of lateral union 
(z.c., in the distinctness of the sutures) between their component joints, which is more 
or less evident in Hyocrinus, Bathycrinus, and Rhizocrinus, appears also in some fossil 
Crinoids. Beyrich has pointed out? that in young individuals of Enerinus gracilis the 
sutures between the basals are invisible, although those between the radials are distinct 
enough ; and the same character has been noticed by Mr. R. Etheridge, jun., and myself 
as occurring in the Palzeozoic Allagecrinus austini.3 
? Journ. Linn. Soc. Lond. (Zool)., vol. xvi. p. 50. 
* Ueber die Crinoiden des Muschelkalks, Berlin, 1857, p. 44. 
* On Allagecrinus, the representative of a new family from the Carboniferous Limestone Series of Scotland, Ann. 
and Mag. Nat. Hist., ser. 5, 1881, vol. vii. pp. 285-288. 
