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



quoted and in the first paragraph of the second one are inaccurate, to say the least of it. 

 Messrs. Vogt and Yung do not name the authors who have used the term " chambered 

 organ" in this " very improper" sense ; but it is certainly neither Dr. Carpenter, Ludwig, 

 Greeff, Teuscher, Marshall, Jickeli, Perrier, nor myself ; and I know of no other original 

 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 1 is the radial portion 

 of the body-cavity within the calyx, which is clearly distinguished from the chambers 

 within the central capsule in all the figures given by Ludwig, Greeff, 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 apj^ear that Dr. Carpenter had made a great mistake, which 

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

 organ" as employed by him and by every one of his successors until now refers exclusively 

 to the cavities within the central capsule, which lie on the dorsal side of the rosette and 

 radial pentagon. But Messrs. Vogt and Yung erroneously interpret it as denoting the 

 entire system of cavities within the centro-dorsal plate and the ring of radials that rests 

 upon it; 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 entirely at a loss to know who the authors 

 can be who have used the term "chambered organ" in the "eminently improper" sense 

 described by 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 perpetuated it both in their text and in the 

 explanations of their figures. Thus in fig. 276 the cavities within the central capsule on 

 the dorsal side of the rosette, and the portion of the body-cavity which is on the ventral 

 side of this structure and is enclosed by one of its radial processes, are marked alike " c,c, 

 cavites dependantes de la cavite generale et constituant dans leur ensemble, l'organe dit 

 cloisonne." No one but Vogt and Yung has used the 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 textbook of comparative anatomy for the use of students. 

 But Messrs. Vogt and Yung go even further than this. The space on the dorsal side 

 of the central capsule which is marked f in fig. 267 and c in fig. 276, and is described 

 as one of the cavities of the chambered organ, is nothing; but a rent in the organic basis 

 of the floor of the centro-dorsal piece. These rents often appear in the skeletal tissues 

 when very thin sections are cut, and I have been familiar with them for years. But I 



1 Op. cit.J, fig. 264 ; c, fig. 276. 



