80 



Classificatiiin of Fishes. 



Classification of Fishes. 



Elasmobrancliii 



or 

 Cliondropterygii. 



SUB-CIASS I.— ELASMOBRANCHII. Jaw-apparatus'^ 



suspended from skull ; no operculum ; dermal 



armour without bone-tissue 



Order I. — PEOt^ELACHii. Paired fins supported by I 



parallel rods of cartilage ; no claspers in | 



male . . . . . . . . , , . . I 



Order II. — Ichthyotomi. Pectoral fins supported | 

 by cartilages radiating from central axis ; I 

 claspers in male . . . . . . . . | 



Order III. — Acanthodii. All fins except caudal [ 

 with spine in front, and cartilages very ( 

 short ; no claspers . . . . . . | 



Order IV. — Selachii. Pectoral fins with two or I 

 three basal cartilages and no central axis ; ] 

 claspers in male 

 Sub-orders. TectospondifU and Asterospondyli 

 StTB-ClASS II. — HOLOCEPHALi. Jaw-apparatus fused 

 with skull ; an opei'cular membrane ; dermal 

 armour without bone-tissue 

 Order 1. — CniMiEEOiDEl. Fins as in Selachii ,.J 

 Sub-class III. — DIPNOI. Jaw-apparatus fused with") 

 skull ; an opercular bone ; dermal armour | 

 often with bone-tissue . . . . . . • • L D' 



Order I. — Sieenoidei. Scaly fishes with jjaddle- f ^^ 

 shaped paii-ed fins, these supported by a | 

 segmented axis . . . . . . . . J 



Order II. — Atitheodiea. Armoured fishes, the*) 

 head-shield hinged on body-shield ; paired 

 fins rudimentary 

 StTB-CLASS IV.— TELEOSTUMI. Jaw-apparatus sus- 

 pended from skull ; an opercular bone ; dermal I 

 armour often with bone-tissue . . . . . . I 



Order I. — Ceossopteeygii. Paired fins paddle- j 



shaped and fringed with fin-rays . . . \ Granoidei. 



Sub- orders. Haplistia, Ithijndistia, Actinis- 



tia, and Cladistia 



Order II. — Actinopteeygii. Supports of paired 



fins much shortened and dermal rays 



chiefly supporting membrane 



Sub-orders. — Chondro.stei, Protospondyli, 



Aetheospondyli, Isospondyli (in pai't)J 



Isospoudyli (continued), Plectospon-^ 



dyli, Nematognathi,JIaplomi,Ap>odes, j 



Aiiacanfhini, Fercesoces, Pharyngo- f-Teleostei. 



gnathi, Percomorphi, Lophohranchil, j 



Hemibranchii, and Pleciognathi ..) 



