DIGESTIVE SYSTEM. 319 



In some cases, the claws in which the toes terminate, by 

 penetrating the substance of the object, retain it more se- 

 curely. These claws are sometimes double on the same 

 finger, and have their motions so arranged, that they seize 

 the object like a pair of forceps. 



In place of arms, protected or supported by hard articu- 

 lated substances, many animals possess soft flexible threads 

 of various thickness, termed tcntacula. These encompass 

 the objects used as food, and convey them to the mouth. 

 Sometimes, for the more certain retention of the prey, 

 these tentacula are armed with suckers, which adhere rea- 

 dily to any surface to which they are applied. 



Some animals are furnished with a lengthened snout, 

 for the purpose of turning up the ground in search of food, 

 as the sow and mole. In the case of the elephant, the 

 snout is so constructed at the extremity, as to grasp an ob- 

 ject, and so flexible throughout, as to serve the purpose of 

 tentacula. 



These organs for seizing which have been enumerated, 

 though, in general, situated in the anterior part of the body, 

 in the neighbourhood of the mouth, do not enter into the 

 composition of that opening. Those which follow, how- 

 ever, form constituent parts of that organ. 



The margin of the mouth itself, termed the lips, is, in 

 many cases, well adapted for the purpose of seizing objects. 

 In some cases, they are capable of being protruded to some 

 distance, and form a tubular proboscis ; and being beset 

 with teeth or prickles, retain possession more secure of the 

 objects of their pursuit. 



In some instances, the tongue is used as an instrument 

 of seizure. In which case it is capable of being extended 

 considerably beyond the margin of the mouth. 



In many aquatic animals, a variety of means are em- 

 ployed, in order to produce currents in the water, to bring 



