476 RADIATA. ANOCYSTI. 



tallizes as rhombohedral lime-haloide upon the body of these animals." 

 We suspect that this acute mineralogist has been deceived by consi- 

 dering as recent what were, in fact, fossil specimens. At least no 

 such crystalline arrangement as is here described, exists in the spines 

 of the recent British Echini, not even in the large prickles of Ce- 

 daris impillata, one-eighth of an inch in diameter. 2. The jointed 

 bodies, which have long been considered as distinct animals, and 

 constituting the genus Pbdicellaria of Midler, are dispersed among 

 the prickles. They are supported on a moveable spinous stalk, en- 

 veloped by the integument, furnished with one or more joints, and 

 terminating in a head, which, when alive, is continually in motion. At 

 the base, where they adhere, a small eminence may be observed, diffe- 

 rent, however, from the ordinary tubercles, with articular surfaces. 

 These are conjectured by Monro to be similar in their functions to the 

 antennae of insects. 3. The suckers are placed on the avenues of pores. 

 They consist of longitudinal and circular muscles, with a terminal disc 

 for adhesion. These are connected with the integument. The perfo- 

 ration in the disc is single, and leads into a canal, which divides and 

 enters the shell by two pores ; each pair of pores belonging to a single 

 sucker. By means of these suckers, assisted by the spines, the ani- 

 mal moves slowly along the rocks in search of food or shelter. The 

 mouth is furnished with five converging teeth, fixed in large complex 

 sockets. These are connected by a strong ligament, with five proces- 

 ses, which project perpendicularly inwards from the margin of the aper- 

 ture, and serve as points of insertion for the muscles of the jaws. The 

 gullet, after some convolutions, enters a larger intestine, which de- 

 scribes some waving circles, and then opens at the vent. The intes- 

 tine is accompanied by a mesentery and two parallel vessels, which 

 probably perform systemic and pulmonic functions. The water is ad- 

 mitted into the interior, for the purpose of aerating the blood by a very 

 singular organization. On the inside of the shell, from the pelvis to 

 the mouth, there is a straight vessel, under the ziz-zag Une of each of 

 the smaller compartments. This vessel, in its course, communicates 

 by parallel lateral canals, with a row of vascular, foliaceous membranes, 

 situate on each side and underneath the avenues of pores. These 

 membranes consist of convoluted anastomosing vessels, communicating 

 by two ducts with two of the external perforated suckers, each sucker 

 sending a tube to two different leaves. These five vessels neai" the 

 mouth, subdivide, enter large receptacles at the base of the sockets of 

 the teeth, and then open externally, probably through the tubular pro- 

 cesses of the oral plate, though, according to Monro, by canals through 



