PREHENSION OF FOOD IN ANIMALS. 573 



soft marine creatures, Pteropods and others, in the interior of the mouth, 

 ready to be swallowed ; lastly, the vegetable-feeding dugong employs its lips 

 and jaws. The ornithorhynchus takes its food by its duck-bill horny mandi- 

 bles. In a few Mammalia, as in certain Quadrumana, Bats, and Rodents, 

 cheek-pouches exist for the temporary reception of food ; these are very large 

 in the hamster and opossum. 



Birds. The raptorial species, and also the parrots, use the foot prehen- 

 sively, as well as the jaws. In most birds, however, the bill is the substitute 

 for the tooth-bearing jaws and fleshy lips of the Mammalia, and the shape of 

 this most characteristic part in Birds, is variously modified to suit the char- 

 acter of the food. Thus, it is short and strong in the granivorous sparrows 

 and linnets ; long and tender in the small insectivorous warblers and fly- 

 catchers ; notched in other insectivorous birds, as in the shrikes ; short and 

 gaping in the swallows and night-jars, which catch their prey upon the wing ; 

 strong and hooked in the rapacious eagles and vultures, which tear up their 

 food ; long, conical, and of great strength, in the digging rook, and in the 

 woodpeckers, which pierce the bark of trees ; short, curved, and of great 

 depth in the parrot tribe, which can crush hard nuts ; exceedingly delicate and 

 tapering in the humming-birds, to enable them to penetrate the tubular co- 

 rollas of flowers ; ponderous and ungainly in shape, in the toucan and the adju- 

 tant ; long, strong, and pointed, for the catching offish, in the herons, storks, 

 and kingfishers ; elongated and suctorial, in the snipes and sandpipers, which 

 seek their food in bogs or sands ; flattened, grooved, and sensitive, in the ducks, 

 geese, swans, and spoonbills ; or it presents still other forms, for holding fish, 

 as in the pelicans, pilgrims, albatross, penguins, and auks. In the cross-bills, 

 the mandibles, when closed, pass by each other so as to present the appear- 

 ance of a deformity, but this peculiar conformation enables them to extract, 

 with great facility, the seeds from the fir cones. The young pigeon is fed on 

 the regurgitated contents of the crop of the mother-bird. This is accom- 

 plished, not, as is usually stated, by the mother placing its bill in the mouth 

 of the young bird, but by the very opposite manoeuvre. The lower mandible 

 of the young pigeon is elongated and boat-shaped, and, for a time, of dispro- 

 portionate size as compared with the upper mandible ; hence it forms a sort 

 of spoon for the reception of the food taken from the gullet of its parent ; as 

 the pigeon grows, the lower mandible becomes relatively smaller (Tegetmeier). 

 In the parrots and woodpeckers, the tongue is prehensile. 



Reptiles. These, like birds, have no lips. They capture their prey with the 

 jaws, which are horny in the Chelonians, have small teeth in the Ophidians, 

 powerful teeth in the larger Saurians, and delicate and even complex teeth in 

 the small insectivorous species. The limbless serpents crush their prey in 

 their coils, before swallowing it. The prehensile tongue of the chameleon is 

 well known. 



Amphibia. In these animals, the soft lips and jaws are sometimes provided 

 with minute prehensile teeth ; the food is taken by a snapping movement. 

 The tongue of the toad has been already referred to (p. 198). 



Fishes. By these, the food is invariably seized by the jaws, which are 

 usually provided with numerous sharp recurved teeth ; though, in some spe- 

 cies, the mouth is suctorial, and the teeth are few, or even wanting. In the 

 amphioxus, the oral orifice is guarded with soft cirrhi, whilst the mucous 

 membrane of the mouth is provided with ciliated processes ; the food is per- 

 haps conveyed into the mouth by ciliary action. 



Mollusca and Molluscoida. The so-called feet of the Cephalopods serve to 

 convey food to the mouth ; but the tentacula generally present in Molluscs, are 

 sensory rather than prehensile, the food being seized by the mouth, as in the 

 terrestrial and in certain aquatic Gasteropods, or brought thither by currents 

 of water caused by movements of the mantle, or by cilia, as in the Lamelli- 

 branchiata. In the molluscoid Polyzoa, the ciliated tentacles around the oral 

 aperture produce a vortex, by which minute organisms in the water are hurried 

 into the pharynx. In the Tunicata, the cilia lining the fore-part of the ali- 

 mentary canal, accomplish a similar purpose. 



Annulosa and Annuloida. Most Annulosa have distinct buccal appendages, 

 consisting of two pairs of jaws ; the first pair are the mandibles or pincers; the 



