46 Traces of Unity in the Appendicular 



are tubercles or spines in one part of the body are teeth 

 in another ; and the only difference between this case 

 and that of the sand-lug already noticed, is that here 

 the teeth are always teeth, and the tubercles or spines 

 always tubercles or spines, and not the one or the other 

 as the proboscis upon which they are implanted happens 

 to be inverted or everted. A similar lesson may also be 

 found in the suckers on the arm of the cephalopod, or 

 in the ambulacral feet and pedicellaria of the star-fish 

 and its congeners : for here the polype-type is still the 

 type, and it is difficult to avoid the conclusion that the 

 parts in which these organs are implanted are, in more 

 than a figurative sense, polyparies. And so likewise 

 with the very hairs, for it is impossible to see the various 

 modifications of these organs articulated and cheliform 

 in the Eunice and many other dorsibranchiate anne- 

 lidans, articulated and ramified in the large bird-spider 

 (Mygale), like the down of birds, &c. without being 

 convinced that the hair is the rudiment of the same 

 part which may be developed into the cheliferous and 

 other limbs of the same or any other creatures. Every- 

 where, indeed, are abounding traces of the same plan : 

 and the inevitable conclusion seems to be, not only that 

 the mandibles and maxillae are con-natural, but that this 

 con-naturality extends equally to the lips and tongue 

 and teeth to all the other oral appendages, and to all 

 the several parts of these appendages, great or small. 

 And if so, then it is possible to see still further in several 

 directions. It is possible to see why it is that the 

 maxillae and the base of the large cheliferous palps of 

 the spider should contain caecal prolongations of the 

 stomach, for this state of things is only a repetition or 

 that which is natural in the ray of the star-fish. It is 

 possible to see why the mandible of the same creature 



