246 ORIGIN OF SPECIES 



be suggested in answer that the voice, which is certainly of 

 high importance to many animals, could hardly have been 

 used with full force as long as the larynx entered the nasal 

 passage ; and Professor Flower has suggested to me that this 

 structure would have greatly interfered with an animal swal- 

 lowing solid food. 



We will now turn for a short space to the lower divisions 

 of the animal kingdom. The Echinodermata (star-fishes, 

 sea-urchins, &c.) are furnished with remarkable organs, 

 called pedicellarise, which consist, when well developed, of a 

 tridactyle forceps— that is, of one formed of three serrated 

 arms, neatly fitting together and placed on the summit of a 

 flexible stem, moved by muscles. These forceps can seize 

 firmly hold of any object; and Alexander Agassiz has seen 

 an Echinus or sea-urchin rapidly passing particles of excre- 

 ment from forceps to forceps down certain lines of its body, 

 in order that its shell should not be fouled. But there is no 

 doubt that besides removing dirt of all kinds, they subserve 

 other functions; and one of these apparently is defence. 



With respect to these organs, Mr. Mivart, as on so many 

 previous occasions, asks : "What v/culd be the utility of the 

 iirst rtiSmentary beginnings of such structures, and how 

 could such incipient buddings have ever preserved the life of 

 a single Echinus ?" He adds, "not even the sudden develop- 

 ment of the snapping action could have been beneficial with- 

 out the freely moveable stalk, nor could the latter have been 

 efficient without the snapping jaws, yet no minute merely in- 

 definite variations could simultaneously evolve these complex 

 co-ordinations of structure ; to deny this seems to do no less 

 than to affirm a startling paradox." Paradoxical as this may 

 appear to Mr. Mivart, tridactyle forcepses, immovably fixed 

 at the base, but capable of a snapping action, certainly exist 

 on some star-fishes; and this is intelligible if they serve, at 

 least in part, as a means of defence. Mr. Agassiz, to whose 

 great kindness I am indebted for much information on the 

 subject, informs me that there are other star-fishes, in which 

 one of the three arms of the forceps is reduced to a support 

 for the other two; and again, other genera in which the third 

 arm is completely lost. In Echinoneus, the shell is described 

 by M. Perrier as bearing two kinds of pedicellarise, one re- 



