36 Dr. P. H. Carpenter on the 



writer on Crinoid morphology who has used the expression 

 " chambered organ " at all. The space represented in the 

 figures to which the Swiss authors refer * is the radial portion 

 of the body-cavity within the calyx, which is clearly distin- 

 guished from the chambers within tlie central capsule in all the 

 figures given by Ludwig, Greeff, Marshall, and myself ; and 

 not one of us has ever regarded this space as a part of the 

 chambered organ, nor, so far as I know, has any other writer 

 on the subject. But from the mode of reference employed by 

 the Swiss authors it would appear that Dr. Carpenter had 

 made a great mistake whicli had escaped notice for twenty 

 years, until it was rectified by Messrs. Vogt and Yung ; 

 whereas in reality they are themselves in error, because they 

 give a meaning to his name which neither he nor any one else 

 who used it ever intended it to bear. The term " (five-) 

 chambered organ," as used by him and by every one of his 

 successors till now, refers exclusively to the cavities within 

 the central capsule, which lie on the dorsal side of the calca- 

 reous rosette and radial pentagon. But Messrs. Vogt and 

 Yung erroneously interpret it as also denoting the entire system 

 of cavities within the centro-dorsal plate and the ring of radials 

 that rests upon it j and this is certainly not a definite organ, 

 but a part of the general ccelom, as stated by the Swiss 

 authors. These facts, however, were perfectly well known 

 both to Dr. Carpenter and to his successors, and I am there- 

 fore entirely at a loss to know who the authors can be wlio 

 have used the term " chambered organ '•" in the " eminently 

 improper " sense described by Messrs. Vogt and Yung. The 

 Swiss authors seem to have entirely ignored or misunderstood 

 the writings of their predecessors, and have attributed to them 

 a mistake which never was made ; but instead of rectifying 

 this supposed mistake they have converted it into a real one, and 

 have per])etuated it both in their text and in the explanations 

 of their figures. Thus in figure 27G the cavities within the 

 central capsule on the dorsal side of the calcareous rosette 

 and the portion of the body-cavity which is on the ventral 

 side of this structure and enclosed by one of its radial pro- 

 cesses are marked alike " c, c, cavites d^pendantes de la 

 cavite gdnerale et constituant dans leur ensemble I'organe dit 

 cloisonnci." No one but Vogt and Yung has used tlie term 

 chambered organ in this sense ; and as they rightly speak of 

 it as " eminently improper," one cannot but regret that it 

 should have been employed in a text-book of compai'ative 

 anatomy for the use of students. 



But Messrs. Vogt and Yung go even further than this. The 

 * Op. cit. : /, WiT. 204 ; c, fig. 270. 



