NO. 39.— 1889.] ZOOLOGICAL TABLES. 187 



parietals not much longer than frontal, in contact with post- 

 oculars ; temporals regular, elongate ; posterior chin shields 

 longer than anterior. 



Then, No. 30, Tropidonotus stolatus, might stand as a 2 . 

 Repeating no characters that are the same as in a 1 , the full 

 description would run thus : One loreal, large, square ; inter- 

 nasals less than half the size of posterior frontals ; supra- 

 ocular not projecting, parietals rounded behind ; superior 

 prse-ocular reaching upper surface of head. 



Or, following Dr. Boulenger, the three following species 

 would read thus : — 



a 1 , Z. mucosus. — Rostral a little broader than deep, visible 

 from above ; internasals about as broad as long, the suture 

 between them shorter than that between the prae-frontals ; 

 frontal as long as its distance from the end of the snout, as 

 long as the parietals, or slightly shorter ; usually three loreals ; 

 five lower labials in contact with the anterior chin shields, 

 which are shorter than the posterior ; the latter in contact 

 anteriorly. 



a 2 , T. stolatus. — Rostral just visible from above ; internasals 

 much narrowed anteriorly, sub-triangular, with the anterior 

 angle truncated, the suture between" them nearly as long as 

 that between the prae-frontals ; frontal longer than its 

 distance from the end of the snout, as long as the parietals : 

 a single loreal as long as deep, or deeper than long ; five to 

 six lower labials. 



a 3 , T. asperrimus. — As in a 2 , but the rostral is visible from 

 above ; frontal sometimes a little shorter than the parietals ; 

 loreal nearly as long as deep ; five lower labials. 



And so the descriptions might be carried on through all 

 the snakes of Ceylon or of the world that have head shields 

 of the type a. But are these minute details of any use to 

 the student, or of any real interest ? 



In the great " Historie Naturelle des Poissons " of Cuvier 

 and Valenciennes the description of the common perch is 

 Kiven with the most precise minuteness, even to the curves 

 of the profile ; but the system is only fitfully carried out. 



