476 
RADIATA. ANOCYSTI. 
tallizes as rhombohedrai lime-haloide upon tbe body of these animals.” 
We suspect that this acute mineralogist bas been deceived by consi- 
dering as recent wbat were, in fact, fossil specimens. At least no 
sucb crystalline arrangement as is here described, exists in tbe spines 
of tbe recent British Echini, not even in the large prickles of Ce- 
daris papillatay one-eighth of an inch in diameter. 2. The jointed 
bodies^ which have long been considered as distinct animals, and 
constituting the genus Pedicellaria of Miiller, 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 sucTcers are placed on the avenues of pores. 
They consist of longitudinal and circular muscles, with a terminal disc 
for adhesion. These ai-e 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 fi’om 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, fi-om the pelvis to 
the mouth, there is a straight vessel, under the ziz-zag line 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 near 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 
