XXXli INTRODUCTION. 



The diameter of the eye is its horizontal, unless its vertical is also given. The comparative 

 size of this organ varies with age, being almost invariably comparatively larger in the immature 

 than in the mature specimen, but even here an exception occurs in the Elops apalike. 



By height of body is meant its greatest vertical diameter. By width of body its greatest 



thickness. 



By spine is meant an unarticulated bony or spinous ray. By ray those which are articulated, 



whether branched or single. 



The measurements are intended to refer to the adult fish. 



In speaking of the origin or commencement of a fin, the anterior extremity of its base is 

 referred to, unless otherwise specified. 



The terms right (dextral) and left (sinistral) are employed with reference to a flat fish when 

 placed with its tail towards the observer, its dorsal fin upwards and its anal downwards. 



The term Seas of India has reference to the sea on the Eastern side of the Peninsula of 

 Hindustan, as well as to that on the "Western. 



Cheltenham, 



August 27th, 1865. 



