CHANGE OF FOOD. 59 



out exception, carnivorous ; those of the Western, on the contrary, 

 chiefly herbivorous. But among the former there are certain 

 species — Lacerta agilis, L. muralis, and others — which some- 

 times, like dogs, eat grass and even fruits. On the Balearic 

 Island of Ayre, close to Majorca and Minorca, lives an entirely 

 blue-black variety of L. muralis, which I myself found there. 

 The island is very barren ; only low shrubs grow on the stony 

 soil, and during the dry months, from June till October, not 

 even burrowing insects are to be found. During this period the 

 lizards feed on plants, and above all on the fruit which is brought 

 in by the inhabitants. I have been able to keep numerous speci- 

 mens which I brought away with me, for months together, even 

 during our northern winter, on sweet fruits, juicy or softened 

 by soaking. Now in all text-books of zoology it is stated that 

 the lizards of the Old World are distinguished by haying teeth 

 connate with the jaw, while the vegetable-eating lizards of the 

 West have teeth which grow in sockets in the jaw. The facts 

 above given suffice to show that this parallel between the 

 nutrition and the animal's place in a system — such as seems to 

 be indicated by the teeth — is in fact defective in individual cases, 

 and we may even hazard a suspicion that it may in great part 

 depend only on insufficient observations of the habits of lizards 

 on the part of zoologists. Most small apes feed on fruits ; 

 amongst them, however, Jachus vulgaris, known as the Mar- 

 moset, is distinguished by an inordinate liking for the ill-smell- 

 ing cockroach, a species of Blatta. Our common perch, as well as 

 a few Cyprinoidee, frequently eat duck-weed (Lemna), although 

 they belong to a group of carnivorous fishes ; squirrels are the 

 greatest enemies of our singing birds, whose eggs and young they 

 devour in great quantities ; individuals of the Russian brown 

 bear will feed on oats, others on honey, others again on ants or 

 meat. In conclusion I will only mention one fact frequently 

 observed in aquaria by myself and by others. The well-known 

 European pond-snail, Lymrwea stagnalis, belongs to a group of 

 MoUusca which all live on vegetable matter ; and their lingual 

 teeth are regarded by malacologists as typical of true plant- 

 eaters. Nevertheless, the Lymnsea is fond of eating the little 

 water salamander, Triton. I have often observed them and- 



