182 Miscellaneous, 



posterior arthrobranch of segment 12, was forked. The bifurcation 

 began close above the base, the two branches being nearly equal to 

 one another in size and having the usual structure. 



8peclinen III. — This specimen preseuted a partial fusion of the 

 fourth and fifth abdominal segments. Looked at from the tergal 

 side the abnormality could not be seen, but the calcified sternal bars 

 were completely fused from the middle line nearly to the attach- 

 ment of the appendage on the right side. On the left of the midfUe 

 line the two sternal bars were separated by a narrow uncalcified 

 portion, and a certain amount of movement between the two seg- 

 ments was still possible, owing to the elasticity of the narrow and 

 partially fused sternal bars. The appendages were normal, but the 

 distance between the attachments of those on segments 4 and 5, left 

 and right, was naturally much less than usual, as the sternal region 

 of these segments was so much reduced in length. 



Cardiff, 

 Jan. 12, 1892. 



The Chromatophores of Cephalopods. 

 By M. Raphael Blanchaed. 



The radiating fibres which are found around the chromatophores 

 of Ccphalopods have been described by various authors as muscles 

 which are inserted into the envelopiug membrane : by contracting 

 they would expand the chromatophore, on relaxing they would 

 permit it to revert to its original condition and to efface itself more 

 or less. 



In the year 1882 I showed that, during the changes of form to 

 which they are continually subject, the chromatophores alone are 

 active. As a matter of fact attentive histological study enables me 

 to state that the radiating fibres are neither muscles nor nerves, but 

 simply fibres of connective tissue, presenting a peculiar orientation 

 in the neighbourhood of the chromatophore, with which, however, 

 they have no connexion. Soon afterwards a perfectly similar state- 

 ment was made by M. Girod ; this very year these observations 

 have received further confirmation at the hands of M. Joubin *. 



Nevertheless it has been recently stated by M. Phisalix t that 

 " the radial fibres are muscles," and he affirms that the expansive 

 movements of the chromatophore '* are determined by the contrac- 

 tion of muscles arranged radially at its equator.'' He mentions 

 elsewhere the writings of M. Girod, M. Joubin, and myself. 



M. riusalix cites, in support of his opinion, the researches of 

 MM. Paul Bert and Fredericq ; but neither of them has verified 

 anatomically the muscular nature of the radiating fibres; if they 

 attribute this structure to them, it is solely because it was admitted 

 by the naturalists of the period. The interesting experiments made 

 by M. Phisalix, following upon those of the two observers mentioned 

 above, are explained by the intimate union of the chromatophore 

 with the nerves. / expresshf recoj)u:ed this union, and the result 

 of my observations appears to me to remain unimpaired. — CompU^ 

 Bendus, tome cxiii. no. 17 (Oct. 2G, 18U1), pp. 505, 50(3. 

 * Ann. .'^ Mh'T. Nat. Hist. 1801, viii. p. 111. t J'ide infra. 



