26 CLASSIFICATION OF FISHES. 



570. Until very recently the classification of Fishes most 

 generally received was that of Cuvier, who made this group his 

 peculiar study. After maintaining its ground as the system of 

 Ichthyology for many years, this classification has recently been 

 nearly superseded by one proposed by Professor Miiller of Ber- 

 lin, which appears to furnish a much better means of arranging 

 the numerous species of Fishes in natural groups ; and this will 

 be adopted, with some modifications, in the present work. As, 

 however, the system of Cuvier was, up to such a recent period, 

 the one to which all authors referred in treating on Fishes, and 

 the large and splendid work on those animals by MM. Cuvier 

 and Valenciennes is arranged in accordance therewith, the fol- 

 lowing short statement of its principal groups will perhaps prove 

 useful to the reader. 



571. The first division of the class is into the Osseous and 

 Cartilaginous Fishes ; and this division has reference not only 

 to the quantity of earthy matter in the skeleton, but also to the 

 number of pieces of which the jaws are composed. The sub- 

 class of Osseous Fishes is divided in the first instance into the 

 groups Acanthopterygii, or spiny-finned, and Malacopterygii, or 

 soft-finned, Fishes. In the former, the first portion of the dorsal, 

 or the first dorsal fin (when there are two), always have spinous 

 rays ( 543); of which there are also some in the anal, and at 

 least one in each ventral. In the latter, all the rays, with the 

 occasional exception of the first dorsal or the pectorals, are soft 

 or jointed. The Acanthopterygii are only subdivided into fami- 

 lies ; but the Malacopterygii are divided into three orders, ac- 

 cording to the position of the ventral fins. If these are situated 

 under the abdomen, the fishes are Abdominal; if attached to the 

 shoulder, they are Sub-brachial; and if wanting, they are Apodal. 

 Each of these orders, especially the first, contains numerous 

 families. Besides these Cuvier admitted two other small orders 

 of Osseous Fishes, namely the Lophobranchii with tufted gills, 

 and the Plectognathi in which the bones of the upper jaw and 

 face are immovably attached to the cranium. 



572. The sub-class of Cartilaginous Fishes is primarily divided 

 into those having the extremities of the gill-filaments unattached 



