284 THE VOYAGE OF H.M.S8. CHALLENGER. 
top stem-joint. A few fossil species, however, have been figured or described as not 
possessing any external basals. Two of these are from British rocks, Pentacrinus fisheri 
and Pentacrinus dixont. The former was described by Baily,’ who was unable to detect 
the presence of interradial basals, and was led therefore to regard the first radials as 
basals. True basals are really present, however, and may be seen in the original 
specimen in the Dorchester Museum, or in another found subsequently and now in the 
possession of Mr. Damon of Weymouth. 
The same is the case with the specimen of Pentacrinus dixoni in Mr. Willett’s 
collection at Brighton, which was figured in Dixon’s Geology of Sussex (1878 edition, 
pl. xix. fig. 22). In both these species, therefore, the supposed absence of basals is 
really due to error; and I think it likely that the same may be true both of Isocrinus 
pendulus, von Meyer, and of the Forest Marble specimen from Farley in Wiltshire, which 
was described by Goldfuss? as Pentacrinus scalaris; and also of Pentacrinus penta- 
gonalis personatus from the Brown Jura. According to Quenstedt * three pieces rest on 
the top of the stem “ womit jedes der 5 Hauptradiale beginnt.” But neither then nor 
in the Eneriniden did he make any comment on the absence of basals, though he 
must have noticed it. They may perhaps be small and only just in contact by their 
central ends, so that they are concealed beneath the radials, as sometimes happens in 
Fnerinus and in the fossil Comatule.* But it appears to me improbable that the 
embryonic basals of any Pentacrinus should have undergone transformation into a 
rosette, as those of many Comatule do, A Stalked Crinoid with a rosette would be a 
novelty indeed. 
One would greatly like to know the real condition of the anomalous specimen of 
Metacrinus costatus represented in Pl. XLIX. fig. 2, which has no basals visible externally. 
They are generally so very well developed in this genus that their absence altogether 
seems unlikely ; and I suspect therefore that they are quite small and concealed between 
the top stem-joint and the radial pentagon, as in the case of Hucrinus and the fossil 
Comatule. 
It is a curious fact that there are so very few species of Pentacrinide with only one 
ray-division, 7.e., with only ten arms; while at the same time the number of arms rarely 
reaches the large total of one hundred or more, as it does in some of the giant species of 
Actinometra from the Philippines. In Pentacrinus maclearanus (Pl. XVI.), Pentacrinus 
wyville-thomsoni (Pls. XVII, XIX.), Pentacrinus alternicirrus (Pl. XXV.), Pentacrinus 
blake: (Pl. XXXI.), and Pentacrinus decorus (Pls. XXXIV.-XXXVIL), the rays may 
divide three times, t.e., there may be distichal and palmar axillaries above the radials. 
* Description of a new Pentacrinite from the Kimmeridge, cf. Oxford Clay of Weymouth, Dorsetshire, Ann. and 
Mag. Nat, Hist., ser. 3, vol. vi. pp. 25-28, pl. i. 
? Petrefacta Germanie, vol. i, pl. lx. fig. 10. 
3 Der Jura, 1858, pp. 363, 364. 
4 Journ, Linn. Soc. Lond. (Zool.), vol. xv. p. 195, pl. ix. fig. 6. 
