THE FISHES OF INDIA. 



CLASS PISCES. 



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

 extremities modified into fins. Bespiring;, 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 OF STJB-CLASSES. 



I. Tblbostbi or Eleutheeobranchii. Skeleton osseous. Brain, distinct. Sknll possessing cranial bones. 

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

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

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

 commencement. 



II. Chondeopteetgii or Elasmobeanchii. Skeleton cartilaginous. Brain distinct. Sktdl without 

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

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

 mencement. 



SYNOPSIS OF ORDERS AMONGST THE TELEOSTEI. 



I. AcANTHOPTEETGii. 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. Anacasthini. All the rays of the vertical and ventral fins articulated ; the latter, when present, being 

 jugular and thoracic. 



III. Phtsostomi. AU 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 ScombresocidoB). 



rV. Lophobeanchii. Fishes possessing a dermal segmental skeleton, with the opercular pieces reduced 

 to a single plate. GUI-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. Plectognathi. Fishes with the bones of the head completely ossified, whilst those in the remainder 

 of the body are incompletely so : vertebrae few. GiU-openings small, situated in front of the pectoral fins. GiUs 

 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 : veatrals when existing, have the form of spines. Skin either smooth, with rough ' 

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



OeogrwpUeal distribution. The Acanthopterygian Fishes 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 tie LabyrmtUci and OphiocephaUdce can live in water even with a bandage fastened round their gills, entirely- 

 preventing their use 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. 



t There are some genera in which the fins can hardly be said to possess any true spines as amongst the TrachMdae, AuUstoma- 



Wdce, Trachi/niaUB, &c. 



B 



