DEFECTIVE EYE-SIGHT. 357 



distal extremities of both jaws are without teeth ; while there are 

 ninety-two teeth in the hinder parts of the jaws, and these, as with 

 other reptiles, were replaced by new ones as fast as they wore out. 

 The skin was smooth, or covered only with epidermic scales. Some 

 observers believe they have found in the foot-prints evidences that a 

 slight web existed between the toes. M. Dollo has drawn a conjectural 

 outline of the body of the iguanodon, which is represented in our large 

 cut. Leaving out the long tail, its general shape is that of a duck. 

 The sectional view, represented by X in the cut, indicates that the 

 animal was relatively very narrow and sharp-keeled, like a clipper-ship. 

 The tail, shaped like that of a crocodile, was probably a powerful 

 swimming organ, like that of the duck. The neck was comparatively 

 slender and capable of very free movements. The animal was an in- 

 habitant of marshes — so far as is known, of fresh- water marshes only 

 — and probably fed largely on ferns, abundance of which were found 

 with the Bemissart specimens. 



A multitude of other treasures besides the iguanodons were found 

 at Bernissart, and are awaiting careful examination. Among them 

 are crocodiles, in which two new genera have been defined ; turtles, 

 which have given one new genus ; and " a vast quantity of fishes." 



DEFECTIYE EYE-SIGHT. 



By SAMUEL YOEKE AT LEE. 



DETERIORATION of the eye has been, for many years, a topic 

 of complaint — not only in the United States, but in Europe. In 

 Germany, after a careful examination of the pupils in a public school, 

 a surgeon has reported that the proportion of normal-sighted children 

 is gradually less as the ages of the subjects advance : being thirty- 

 six per cent in the primary classes to ninety per cent in the highest 

 classes. Another German investigator reports that, from an examina- 

 tion embracing ten thousand children, it was found that the number 

 of short-sighted in the elementary classes was from five to eleven per 

 cent ; in the higher school for girls, the proportion was from ten to 

 twenty-four per cent ; in the Mealschulen, it was between twenty and 

 forty per cent ; in the gymnasia, between thirty and fifty per cent ; 

 and in the highest classes of all, between thirty-five and eighty-eight 

 per cent. In an examination of six hundred students of theology 

 at Tabingen, it was found that seventy-nine per cent suffered from 

 myopia. 



Similar examinations made in the schools of France and of Eng- 

 land exhibit similar results, showing that the organ of sight grows 

 weaker as the term of study grows longer. In the United States, 



