404 KANSAS CITY REVIEW OF SCIENCE. 



Mr. AUinson contends, the first forms of animal life must have nourished them- 

 selves upon vegetable matter. Hence the question when and how animals be- 

 came zoophagous is perfectly legitimate. 



But at the same time we must recognize that among vertebrate animals, and 

 especially among Mammalia, the earliest forms seem to have been zoophagous. 

 Among fishes^ amphibians, and reptiles, even in the earlier geological epochs, 

 the vegetable feeders are found in a minority. The earliest birds, such as Archce- 

 opteryx, Hesperornis, Ichihyornis, and Apatornis, which approach nearest to rep- 

 tiles, and which were probably all armed with teeth — were plainly fitted for a 

 predatory life. Among mammals the lowest and earliest forms are decidedly 

 zoophagous. This is the case with the monotrematous genera Echidna and Or- 

 nithorhynchus, and also with not a few of the marsupials, both recent and fossil. 

 The oldest of the true placental mammals are the Insectivora, including the hedg- 

 hog, the shrews, moles, etc. Yet few of these animals partake of vegetable food, 

 save under the pressure of necessity. Nor do they by any means confine their 

 depredations to insects. The hedgehog merits the favoring notice of man as be- 

 ing a destroyer of vipers, but at the same time it excites the wrath of the sport- 

 ing world by its raids upon the eggs of the pheasant and partridge, and even upon 

 the young birds and upon leverets, and is, for his size, as clearly a beast of prey 

 as is the tiger. 



It may even be permissible to ask whether among the mammals the purely 

 phytophagous forms have not been developed from a zoophagous, or at least 

 from an omnivorous, stock? The only large group which, according to our pre- 

 sent knowledge, contains no zoophagous or omnivorous members, is the old order 

 Ruminantia. Now this suborder, which is first traced in the Eocene Tertiaries, 

 isxharacterized by its complicated and highly specialized digestive organs, evi- 

 dently modified from the normal mammalian type, so as to be adapted to a pure- 

 ly vegetable diet. This same structure, or at least one highly similar, is met 

 with again among the sloths, the only phytophagous section of the Edentata. 



The next consideration is that numerous animals which are zoophagous at 

 one epoch of their life may be phytophagous at another, whether earlier or later. 

 This change is not accidental or compulsory, but ensues naturally and normally 

 in every individual of the species in question. Thus all mammalian animals, 

 whatever may be their future diet, begin life as zoophagous beings so long as they 

 are nourished on their moth's milk. Indeed it is fully proved that e. g., the hu- 

 man infant is for some time incapable of digesting vegetable matter. 



Among birds we meet with the same fact. Setting aside the many groups 

 which are zoophagous throughout life, we find that, as a rule, the young of the 

 seed- and fruit-eating species require an exclusively animal diet, consisting of in- 

 sects, worms, etc. In other cases they are fed with half-digested food disgorged 

 from the crop of their parents. There are few, if any, cases where a bird when 

 just hatched is able to feed on crude vegetable matter. 



Among insects many similar changes take place. The robber-flies of the 

 genus Erax, which in their adult state destroy numbers of hive-bees, feed when 



