

THE PISHES OE INDIA. 



CLASS PISCES. 



Vertebrate animals which are, as a rule, exclusively adapted for an aquatic life, and have their 

 extremities modified into fins. Respiring, almost invariably, solely by means of gills :* possessing a heart 

 with only two cavities, and being cold-blooded. They are scaleless, partially or wholly scaled, the scales being 

 sometimes in the form of osseous plates. 



SYNOPSIS OP SUB-CLASSES. 



I. Teleostei or Eletjtheeobeanchii. Skeleton osseous. Brain distinct. Skull possessing cranial bones. 

 Vertebras completely separated, and the posterior extremity of the vertebral column bony, or having bony plates. 

 Branchias free, and the water discharged through a single aperture on either side, protected by a bony gill-cover 

 or opercle : branchiostegal rays present. A non-contractile bulbus arteriosus, having a pair of valves at its 

 commencement. 



II. Chondropteetgii or Elashobeanchii. Skeleton cartilaginous. Brain distinct. Skull -without 

 cranial sutures. Gills pouch-like, and attached by their outer edge to the skin, whilst an intervening gill-opening 

 exists between each. No gill-cover. Bulbus arteriosus contractile, and having three rows of valves at its com- 

 mencement. 



SYNOPSIS OP ORDERS AMONGST THE TELEOSTEI. 



I. Acanthoptebygii. A portion of the dorsal, anal, and ventral fins unarticulated, forming spines.f Air- 

 vessel, when present, completely closed, not possessing a pneumatic duct. 



II. Anacanthini. AH the rays of the vertical and ventral fins articulated ; the latter, when present, being 

 jugular and thoracic. 



III. Phtsostomi. All the fin rays articulated, with the exception of the first in the dorsal and pectoral 

 which sometimes are more or less ossified. Ventral fins, when present, abdominal and spineless. Air-vessel, if 

 existing, having a pneumatic duct (except in Scombresocidce). 



IV. Lophobeanchii. Pishes possessing a dermal segmental skeleton, with the opercular pieces reduced 

 to a single plate. Gill-openings small. Gills consisting of small rounded tufts, attached to the branchial arches. ' 

 Muscular system very slightly developed. Snout produced : mouth terminal, but small. Teeth absent. Air- 

 vessel stated to be destitute of a pneumatic duct. 



V. Plectognatht. Fishes with the bones of the head completely ossified, whilst those in the remainder 

 of the body are incompletely so : vertebras few. Gill-openings small, situated in front of the pectoral fins. Gills 

 pectinate. Head generally large. Mouth narrow : the bones of the upper jaw mostly united, sometimes produced 

 into the form of a beak. Teeth in the jaws absent or present. There may be a single soft-rayed dorsal fin, 

 belonging to the caudal portion of the vertebral column, and situated opposite the anal : in some a rudimental 

 spinous dorsal is also present : ventrals when existing, have the form of spines. Skin either smooth, with rough 

 scales, or ossified in the form of plates or spines. Air-vessel destitute of a pneumatic duct. 



Geographical distribution. The Acanthopterygian Pishes do not exist in any numbers in the inland 

 fresh- waters of India, being mostly confined to either within, or but a short distance removed from tidal 



* Certain fish as the Ldbyrintlvici and OphiocepJialidoi can live in water even with a bandage fastened ronnd their gills, entirely 

 preventing their nse for respiratory purposes, provided they can obtain direct access to atmospheric air. Such a proceeding would however 

 be fatal to the majority of fishes, thus showing that some forms possess means of depurating their blood which are not present to all. 



f There are some genera in which the fins can hardly be said to possess any true spines as amongst the Trachinidce, Aulostoma- 

 tid/z, Tmchinidce, &c. 



B 



