324 THE ORIGIN OF SPECIES 



harmlessly on each side of this elongated larynx, and so 

 safely attains the gullet behind it." Mr. Mivart then 

 asks how did natural selection remove, in the adult kan- 

 garoo (and in most other mammals, on the assumption 

 that they are descended from a mursupial form), "this at 

 least perfectly innocent and harmless structure?" It may 

 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 swallowing solid food. 



We will now turn for a short space to the lower 

 divisions of the animal kingdom. The Echinodermata 

 (star-fishes, sea-urchins, etc.) are furnished with remark- 

 able organs, called pedicellariae, 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 firm hold of any object; and- 

 Alexander Agassiz has seen an Echinus or sea-urchin 

 rapidly passing particles of excrement 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 would be the 

 utility of the Jirst rudimentary beginnings of such struct- 

 ures, and how could such incipient buddings have ever 

 preserved the life of a single Echinus?" He adds, "not 

 even the sudden development of the snapping action could 



