188 



JOURNAL, R.A.S. (CEYLON). 



[Vol. XI. 



It would be impossible to compare the upper profile of the 

 perch with all other fish of the same family or of the same 

 type of form, nor is it easy to see what use there would be 

 in doing so. In point of fact the greater number of the 

 descriptions in this work are as short as those given in the 

 "British Museum Catalogue of Fishes," although by no 

 means so precise. 



There are only sixty species in the following table. In 

 treating of the birds of Ceylon (320 species), or of the fish 

 (between 800 and 900 species), even giving separate tables 

 for such groups as may be characterised as Orders, the omis- 

 sion of minor details would be an absolute necessity if the 

 requisite compression of space is to be obtained. 



The index figures, therefore, under head shields are only 

 used to point out the more striking characters, and those most 

 useful, for the purpose of identification. There are many 

 differences between Nos. 16, 25, 26, 29, 30, and 31, but as in 

 all the nasal is completely divided into two, the loreal single 

 and squarish in form, and all the labials reach the labial 

 margin, and the supra-ocular does not project, they are 

 arranged under a 2 . 



In the case of No. 32, Tropidonotus plumbicolor (head 

 shields a 3 ), the index figure only points to a tendency to 

 vary, not to any absolute character always diagnostic of that 

 species. Such licenses must be allowed if an attempt is to 

 be made to follow the endless variations, gradations, and 

 combinations to be found in any long series of animals. 



Eyes, Nostrils, Mouth, Teeth. 



The eyes, nostrils, and mouths of snakes vary little ; when 

 they do they give the student easily-seized points for finding 

 out what is before him. The visibility or invisibility of the 

 rudimentary eye in the little species of Typlilops will furnish 

 him with important aid in the most difficult task the Ceylon 

 Ophiologist has to encounter, viz., name these little worm- 

 like snakes. Finally, he has to examine the teeth. This is 

 best done by carefully cutting out the jaws and palatine 



