Morphology (^/Antedon rosacea. 31 



not the same as that marked e in fig. 264. The latter is 

 rightly described in the explanation of the figure as the " an- 

 neau pentagonal du sjst^me nerveux central ;" but it lies 

 within the substance of the first radials, above the rosette in 

 the natural position of the animal, and not within the " som- 

 met de la coupole." On the other hand, the part marked g 

 in fig. 276 really is within the centro-dorsal, or summit as the 

 authors call it ; but it is represented above the rosette (of Dr. 

 Carpenter) in their (inverted) fig. 276, while the " mince 

 plafond calcaire," which they describe as separating it from 

 the rosette, whatever this may be, is nothing but the rosette 

 of metamorphosed basals, as described by Dr. Carpenter and 

 all his successors. 1 know of no other thin calcareous plate 

 in the neighbourhood of the chambered organ which at all 

 answers to the description of Messrs. Vogt and Yung. A 

 portion of this calcareous rosette is excellently shown between 

 the ventral surface of the chambered organ {sensu strictu) 

 and the inner face of the first radial, and is marked o in 

 fig. 276 ; but o is left without notice in the explanation of 

 the figure ; and Prof. Carl Vogt has been good enough to in- 

 form me by letter that the missing legend should run " o, 

 tissu conjonctif ar^olaire entourant I'organe dorsal et les 

 cavit^s c de I'organe cloisonne." 



Now this very part had been figured in the sections of 

 Ludwig, Marshall, and myself, and in each case had been 

 marked "Kosette" and its real nature properly explained. 

 It was therefore with no small feelings of astonisliment that I 

 found one of the authors of a work on comparative anatomy 

 describe a calcareous structure which is universally recog- 

 nized as homologous with the genital plates of an Urchin, as 

 " areolar connective tissue." This statement helps us to 

 understand why a portion of the centro-dorsal piece in imme- 

 diate contact with the nervous " anneau central " is lettered 

 " e, mesent^re." 



The authors'* want of acquaintance with the mutual rela- 

 tions of the hard and soft parts in the calyx of Antedon 

 rosacea is further indicated by their description of the mode 

 in which the great brachial nerves originate from the central 

 nervous organ. On p. 549 they say with respect to their 

 vertical sections : — " On voit sur ces coupes la masse nerveuse 

 comme un gateau a face dorsale un peu borabee, tandis que 

 la face ventrale est un peu creuse, et lorsque la coupe a bien 

 rencontrd, comme sur notre figure k droite, I'axe d'un radial, 

 on peut suivre la continuation immediate et sans interruption, 

 sous forme de nerf, de I'un des angles du gateau dans le bras 

 naissant." Now, if the authors had properly studied any one 



