18;2 FOURTH REPORT — 1834. 



siinie time that every attempt is made towards generalization, it 

 will be thought impossible to speak too highly of its merits. It 

 is almost a perfect model for works of this nature, and deserves 

 to be consulted by all naturalists engaged in similar undertak- 

 ings. It cannot but be a subject of deep regret that its talented 

 author has not lived to complete a work, for which he tells us he 

 had been forty years collecting materials. Let us hope, however, 

 that this may be yet effected by M. Valenciennes, Mhom, fortu- 

 nately for the scientific world, M. Cuvier had from the begin- 

 ning engaged as his coadjutor. 



A slight modification of Cuvier's arrangement appears in the 

 Saggio di una Diiitrihuzione,8)C., of C. L. Bonaparte, published 

 in 1S31, principally as regards the value of some of the groups. 

 In the first place, the osseous and cartilaginous fishes are con- 

 sidered as two subclasses. The former are then primai'ily di- 

 vided into three sections: 1. Pectinibranchii, comprising 

 the two orders ^-Icaiithopten/gii and Maiacopterygii; 2. Lo- 

 PUOBRANCHii, including the single order of Osteodermi {Syn- 

 giiathus); and 3. Plectognathi, comprising the two orders 

 Gymnodontes and Sclei'udermi. The Malacopterygii are sub- 

 divided into the three tribes of Ahdomhudes, Suhbrachkmi, and 

 uipodes. Thus we have two of Cuvier's orders raised to a higher 

 rank than that Mhich he assigned to them ; while on the other 

 hand there are three lowered to a subordinate denomination. 

 In like manner we have the cartilaginous fishes divided into the 

 two sections of Chismopnei and Trematopnei : the former 

 comprising the two orders of Eleutheropomi [Sturiones) and 

 Acanthorrhmi {Chimieriv), the latter those of Plagiostomi and 

 Cyclostomi. A similar alteration in the value of some of Cuvier's 

 groups will be found here. 



The most recent work on ichthyology, and one of the most 

 important which has yet appeared, is that by M. Agassiz, now 

 in course of publication*. Although the object of its author is 

 more particularly to illustrate the fossil fishes, it is his intention 

 to bring forward an entirely new classification of fish in general. 

 The details of his arrangement are not yet published. He has, 

 however, put forth a slight sketch of his system, such as will 

 serve to show the striking changes which he contemplates in 



* Reclicrclies stir les Poissons Fossiles, par Louis Agassiz, 1833, &c. Only 

 two numbcvs have hitherto appeared. — M. Agassiz was before known to ich- 

 thyologists from having assisted Spix in the description of his Fishes of Brazif. 

 This work was published in 1829 under tlie following title: Selecla Genera el 

 Species Pisvium quos in Ilinere collegit Spix ; descripsit L. Jgassiz. fol. lu 

 18;5f), M. Agassiz had also announced the prospectus of a work on the Fresh- 

 iiater Fishes of Europe. This last has, however, not yet appeared. 



