ECHINUS. 125 



it genei'ally lies motionless on the base or the vertex, according as it 

 falls on either. But some of the spines very soon begin to move, and 

 these are followed by the suckers. Evident exertion is employed to gain 

 a suitable position for the subject traversing its prison. If a portion of 

 food be now dropped into the vessel, the Echinus speedily becomes sen- 

 sible of its presence. Should the creature be above, the suckers extend, 

 and its descent commences immediately, as it hastens to the repast. 



It is one of the most voracious and promiscuous feeders, always 

 ready to eat, nor is any animal better qualified for the destruction of 

 others with impunity to itself The strength of the teeth is marvellous, 

 and, as if to prove auxiliaries, the principal power for the capture of 

 prey seems to reside in the suckers near the mouth. 



But the most singular and complicated part of the dental apparatus 

 is contained mthin. It is scarcely to be described, and can be inspected 

 only by sawing off" a segment of the under part of the shell, which I have 

 called the base. Then it is discovered to consist of so many parts, 

 operating by such complex movements, that I should despair of ex- 

 plaining the province and effects of almost the whole. The five cutters, 

 compounded as a large inverted cone, projecting below with its vertex 

 as a point beyond the level of the shell, destroy the hardest substances. 

 — Plate XXXI. fig. 2, a. The pomted cutter, fig. 5, is lodged mthin 

 two hollow prisms, figs. 3, 4, as in a case. On inspecting the inside of 

 the sundered segment, a vertical ring, consisting of five staples, is seen 

 considerably elevated above the inner surface of the shell, suiToundmg the 

 orifice of the mouth, into which staples various ligaments secure the base 

 of the inverted cone, fig. 7, a, a, a. The whole apjsaratus is represented 

 along with a section around the mouth, fig. 6, a, a, a, being the upper 

 ends of the teeth, in sitn within the Echinus, and as in fig. 2, f>, l>, I), f>. 



But I repeat, that nothing short of actual inspection can convey an 

 explanation of the operation of the various parts, and then- action. The 

 structure of the mouth of this animal offers a remarkable instance of 

 natural mechanism. 



These ci'eatures often devour pure shelly matter, as appears from 

 the numerous pellets discharged. The fishermen believe that they like- 



