268 THE VOYAGE OF H.M.S. CHALLENGER. 



" Travailleur " examples of this species as a new generic type Democrimis^ which is 

 really, however, only a synonym of RMzocrinus. His account of Democrinus was as 

 follows : — ■" Le Democrinus se distingue immediatement de tous les autres genres par la 

 composition de son calice forme de cinq longues basales constituant h. elles seules un 

 calice en entonnoir ; un sillon circulaire separe ces cinq basales de cinq radiales rudi- 

 mentaires, en forme de croissant, alternant avec elles et surmontees elles-memes de cinq 

 radiales axillaires libres, rectangulaires, mobiles, sur lesquels se fixent respectivement 

 cinq bras, beaucoup moins larges que les radiales. Ces bras se brisent tres facilement au 

 niveau de leur articulation avec les radiales axillaires qui se rabattent alors sur la votite 

 du calice." He further adds that in Rhizocrinus " les basales sont confondues et le calice 

 forme en partie de radiales." The basals of Rkizocrinus, hoTvever, are very far from being 

 "confondues," but are large and independent, as was pointed out by Pourtales in 1868 

 and 1874, and by myself in 1877 and 1882. But Perrier, unaware of this fact, was 

 unfortunately misled by the erroneous descriptions of the basals as internal and concealed 

 which were given by Sars and Ludwig {cinte, pp. 249-251); so that when he found 

 a Rhizocrinus-\\kQ form with long and well defined basals, he naturally (though 

 erroneously) considered it as new to science. 



Although, however, the radials of Democrinus may be small and rudimentary 

 externally, there is no reason why the calyx should consequently be considered as formed 

 by the basals alone ; though Perrier regards this as another character distinguishing 

 Democrimis from Rhizocrinus. In one of the specimens of Rhizocrinus lofotensis which 

 was figured by Sars ^ the radials are quite small externally ; but they have large distal 

 faces for the attachment of muscles and ligaments, the inner surfaces of which form the 

 funnel lodging the lower part of the coelom. The same is undoubtedly the case with 

 the radials of Democrinus, to which the movable first brachials (axillaries, Perrier) are 

 attached just as in Rhizocrinus. 



It is difiicult to understand why the radials of this type should be considered as 

 forming part of the calyx, while those of Democrinus are excluded from it on account of 

 their smaller size. On the same principle one would have to describe the cup of those 

 species of Antedon in which the first radials do not appear externally, as formed by the 

 centro-dorsal only ! 



Prof. Perrier describes the rudimentary radials of Democrimis as separated by a 

 circular furrow from the basals below them. But a drawing of the type which he has 

 kindly sent me, shows that while the basiradial suture is marked by five strong 

 elevations with intervening depressions in which the radials rest, the furrow crosses the 

 radials at the level of the highest angles of the basals. This furrow is more or less 

 distinct in various specimens of Rhizocrinus raivsoni (PI. IX. fig. 3 ; PL LIII. fig. 8), as 

 has been pointed out already. But it can hardly be said to " separate" the radials from 



^ Comptes rendus, t. xcvi. p. 450. * Crinoides vivants, Tab. ii. fig. 44. 



