402 THE VOYAGE OF H.M.S. CHALLENGER. 
de la ressemblance absolue de ces dix plaques alternes avec celles qui forment le périprocte 
des Oursins et que Lovén a rapprochées, & leur tour, de celles qui constituent le calice des 
Crinoides, opinion que nous aurons prochainement occasion de discuter. L/identité de dis- 
position des plaques dorsales des Caulaster avec celles du calice de Crinoides est évidente.” 
It would appear, however, from the foregoing description that Perrier’s comparison of 
the plates round the dorsal appendage of Caulaster with those forming the periproct of 
an Urchin cannot be followed out in detail. The first row of plates in Caulaster, if 
radially situated as Perrier states, cannot correspond to the first or inner row of the 
apical system of an Urchin; for these last are the genitals, and are situated interradially. 
Their homologues are the plates in the second row of Cauwlaster, which alternate with 
those of the first; while the second ring of plates in the Urchins, the oculars or true 
radials, appear not to be represented in Cawlaster. If Perrier’s description of the positions 
of the plates in this type be correct, its apical system consists, not of genitals and oculars 
(basals and radials) as in an Urchin, but of under-basals and basals ; and the true radials 
must be so small as to have escaped his notice. 
NOTE B. 
(Page 36.) 
On THE Basats oF Fossin CoMATULa. 
In certain fossil Comatule the ends of the basals are visible on the exterior of the 
calyx between the radials and the centro-dorsal. They are sometimes quite small, as in 
some forms of Pentacrinus decorus (Pl. XXXIV. fig. 1; Pl. XXXV. figs. 1, 2; Pl. XXXVI. 
fig. 3); while in other species, such as Solanocrinus scrobiculatus, Miinster, they may 
reach a considerable size. As long as basals were supposed to be absent in the calyx of 
the recent Comatule, their presence in fossil forms appeared to be a character of generic 
value. But after the discovery by Dr. Carpenter and Sir Wyville Thomson that the 
Pentacrinoid larva has true basal plates which eventually become metamorphosed into 
the concealed rosette, this distinction between the recent and fossil Comatulz no longer 
holds good. Schliiter* recognised this fact in 1878, and pointed out that Solanocrinus 
was merely a synonym of de Freminville’s name Antedon. He referred to this genus 
both Solanocrinus costatus, Goldfuss, and Solanocrinus scrobiculatus, Minster, together 
with two other fossil species, in both of which the basals appear on the exterior of the 
calyx. Zittel,” however, regarded Solanocrinus as a subgenus of Antedon, distinguished 
from it by the presence of external basals. 
In the following year® the examination of a considerable number of fossil Comatulee 
1 Zeitschr. d. deutsch. geol. Gesellsch., Jahre. 1878, pp. 36, 40. 2 Palontologie, vol. i. p. 396. 
3 On some undeseribed Comatule from the British Secondary Rocks, Quart. Journ. Geol. Soc., vol. xxxvi. 
pp. 36-46, 1880. 
