30 Dr. P. H. Carpenter on the 



travers la pi^ce basale du calice, dans les cirrhes ; " * but 

 what they call the basal piece here is the substance of the 

 centro-dorsal, which they describe elsewhere as the single 

 piece occupying the " summit " of the calyx. This is a con- 

 siderable inconsistency ; but it is only the natural result of 

 their inverted mode of figuring and describing the Crinoid, 

 which also leads them to say (on p. 548) that the cavities of 

 the chambered organ " remontaient dans la tige de la larve 

 pentacrinide lorsque celle-ci dtait encore fixee." 



I have some doubts indeed as to whether they are even 

 aware of the existence of basal plates in Antedon rosacea. 



On p. 529 they say with reference to the first radials that 

 " ils sont fusionnes ensemble et avec une mince plaque treil- 

 lissed, qui s'interpose entre eux et la plaque centro-dorsale, 

 et qui en est separee dans la stade pentacrinoide. Cette 

 partie appellee rosette par Carpenter, montre au milieu une 

 excavation pentagonale a angles prodminents et arroudis." 

 Now this rosette was shown by Dr. Carpenter to be developed 

 by the metamorphosis of the basal plates of the early larva ; 

 and Messrs. Vogt and Yung's description of it as being sepa- 

 rated from the centro-dorsal and radials during the Penta- 

 crinoid stage is incomplete, to say the least of it, seeing that 

 it is not then existent. Dr. Carpenter described the trans- 

 formation of the basals into the rosette as commencing after 

 the detachment of the young Antedon ; and he gave figures 

 of the calyx both of the advanced Pentacrinoid and of the 

 young Antedon in which five separate basal plates are still 

 distinctly visible and the rosette is not yet formed f. 



Although the word " Rosette " as employed by Dr. Carpenter 

 for the metamorpliosed basals of Comatula3 has been used by all 

 subsequent writers on the subject, e. g. Sars, Wyville Thomson, 

 Ludwig, Marshall, Claus, Zittel, Wachsmuth and Springer, 

 Schliiter, Weinberg, Dendy, and myself, Messrs. Vogt and 

 Yung have seen fit to transfer it to another structure, namely 

 a portion of the vascular system belonging to the chambered 

 organ. It is used in this sense on p. 555^ and also three 

 times in the last paragraph of p. 548 ; but in the preceding 

 paragraph we read : '' La partie centrale du syst^me nerveux 

 (e, fig. 264 ; g^ fig. 276) est en effet situde dans le sommet 

 de la coupole au-dessous de la rosette, dont elle est separde 

 par un mince plafond calcaire, perce au centre par de nora- 

 breuses lacunes qui sont en relation avec I'organe cloisonnd." 

 I must confess that this sentence puzzles me. The central 

 part of the nervous system which is marked g in fig. 276 is 



* Op. cit. p. 549. 



t Phil. Trans. 1866, p. 744, p\ xli. figs. 5, 6, pi. xlii. figs, 2, 6. 



