232 THE AQUARIAN NATURALIST. 



the Echini, of which no satisfactory explanation has 

 been as yet given. Numerous short, hair-like ap- 

 pendages, each having a peculiarly constructed sum- 

 mit or extremity, are interspersed amidst the spines 

 of the Echinus, and apparently implanted on the epi- 

 dermis of the shell ; to these structures Miiller, who 

 deemed them parasitical animals, gave the name of 

 Pedicellaria. The Pedicellariae are, in truth, void of 

 any resemblance in form, action, or substance, to the 

 spines or suckers. They present themselves under 

 two different aspects ; but whether these are merely 

 different stages in the growth of the same object, still 

 requires investigation. In one set of these organs, 

 the hair-like stem is crowned with a globular struc- 

 ture of solid appearance ; in the other, the summit is 

 divided into three leaf-like blades, which are capable 

 of opening and closing like a three-bladed forceps, so 

 as to clasp and retain minute fragments between 

 them. The hair-like stem is cylindrical, and contains 

 in its centre a jointed calcareous framework somewhat 

 resembling the stem of an Encrinite (PL IV. fig. 6 b). 



These Pedicellariae cover the Echinus by thousands. 

 They are of various dimensions, in large specimens 

 some of them being half an inch in length. When 

 seen rising from the fine red epidermis of the living 

 Echinus, the movements of these remarkable append- 

 ages are very conspicuous, as they bend from side to 

 side, the head of each describing nearly a circle, and 

 the pincers opening and shutting with great vivacity. 



From the nature of the localities they frequent, 

 the Echini are necessarily much exposed to bruises 

 and other injuries; their foes likewise, both in the 



