I 
228 ECH] 
and flat, or convex, or oval, or conical. Several of them 
have the compartment* furnilhed within with five fila¬ 
ments running round the mouth, which unite, and 
Itrengthen the five lobes of which the body of the animal 
is conftituted. The marks of this reparation into five 
lobes is always vifible externally ; for in every one wc 
may obferve five (triae, or futures, or furrows, either Angle 
or double, or tome other figure confiding of five lines. 
The pieces of the (hell or covering, which are fome hun¬ 
dreds in number, are mofily hexagonal : and upon each 
there is a warty tubercle, (called by Knorr inamellon, nip¬ 
ple,) or elfe a round cavity, which holds the fpine by 
means of a tendon which runs through the center of the 
tubercle or cavity. An union of all thefe pieces makes 
up the five lobes ; and thefe by a very regular future are 
thcmfelves joined as the bones of the cranium are by 
their futures. The fpines are either thick or thin, frnooth 
or rough, fhort or long, apd of various fliapes, fometimes 
as thin as a bridle or hair ; their colour is alfo variable ; 
being white, red, green, brown, black, violet, yellow, 
and variegated. The fpines are ufed by the animal both 
for defence and for motion, and he can raife or deprefs 
them at pleafure. If we offer to drag one of thefe; ani¬ 
mals from a hole in a rock, he raifes his fpines all round, 
and fixes them fo firmly againft the Tides of the hole, that 
it is impoflible to draw him out. When they would re¬ 
move from one place to another, they make ufe of the 
longed fpines, which they move either all together, or 
one after the other, fomewhat like a man walking with 
crutches. In this manner they proceed at a tolerable 
rate, efpecially on the firm banks. But they are never 
feen rolling like a ball, for they can dop themfelves in a 
moment by pufhing out fome of their fpines ; and, if by 
any accident they are thrown topfy-turvy, they can turn 
by means of their fpines, in the fame manner as a beetle 
ufes its legs when thrown on its back. Thefe fpines, as 
before obfcrved, are attached by a thin tendon to the tu¬ 
bercles; but the dighted touch brudies them off when 
the animal is dead ; and hence the fea-urchins preferred 
in cabinets are mod frequently without prickles. To 
keep them entire, they diould be immerfed in fpirits as 
foon as taken out of the fea, that the fpines may diffen, 
and coalefce more firmly. The hard fitrface of the fhell 
is covered with a very thin epidermis, which feems faden- 
ed to the body by an infinite number of filaments, padlng 
through as many minute holes, or ppres, in the covering, 
and holding together the numerous pieces of which it 
confids. Thefe pores, almod imperceptible to the naked 
eye, are commonly placed in ten regular rows, which form 
an arc reaching from the vent to the mouth of the animal. 
Mod of the echini have five large efcutcheons, covering 
the five divifions ; and at the edge of each efcutcheon is a 
regular row of large tubercles, behind which is a row 
containing many hundreds of minute pores ; but in the 
middle of each efcutcheon, indead of pores, are many 
finall tubercles placed without order. Thus the efcut¬ 
cheons, being joined two and two by a regular future, 
form two rows of tubercles, on each fide of which are 
the rows of pores, thus forming ten rows. In other fpe- 
cies, which have no tubercles, the fpines arife from fmall 
points on the fhell, or from little circular indentations. 
The echini were orginally divided by Linnceus into two 
clafl'es only : i. the fea-urchins with the mouth at the 
bafe, and the anus at the apex ; 2. mouth and vent both 
at the bottom. But it has been fince found necellary to 
form more divifions, and fubdivifions likevvife. 
I. Vent vertical ; tentacula every where fnnple. 
Hemifpherical or globular. 1. Echinus •efculentus, 
the efculent fea-urchin. This is fubglobular, with ten 
avenues of pores, the fpaces between covered with fmall 
tubercles fupporting the fpines, which are lharp and 
idrong, above half an inch long ; commonly of a red or 
violet colour ; moveable ; the tubercles elegantly dil- 
pofed in rows'. Thefe are found in the European and 
3 
: n u s. 
Indian feas. In old times they were a favourite didi, and 
thought grateful to the domacb ; they were the fil'd difh 
in the famous fupper of Lentulus, when he was made 
flamen Martidlis , or pried of Mars. This fpecies is exhi¬ 
bited in the annexed engraving, without fpines, at fig. 1. 
The entire animal is armed like the back of a hedge-hog, 
and appears of a reddifii or yellowifh colour, the fpines 
faintly violet, purple, or reddifli ; they are fmooth, l'olid, 
and fo hard, that if they fall on boards or done, they 
found like metal. At the lower extremity, which is 
fomewhat thicker, each fpine is hollowed to embrace the 
top of the tubercle, as reprefented in the engraving at a. 
There is a variety, of which the prevailing colour is white* 
and the fpines brown. 
2. Echinus fphasra : fubfpherical, red, with blueifh 
fpines. This is plentifully found in the Northern Seas. 
3. Echinus draebachienfis : hemifpherical, pale, with 
long pale fpines; likewife an inliabitant of the North. 
Seas. 
4. Echinus miliaris: hemifpherical depreded, with; 
ten avenues of pores, the fpaces between with two rows 
of protuberances. The fpines are dark green ; and round 
the bafe of each is a round knob, or feveral knobs one 
under the other, at the bottom of which is the hollow 
which joins the tubercle. The tubercle is almod fphe- 
rical, and dands on a rifing of the diell, fo as to reprefent 
a wart or nipple. There is a variety which is green and 
reddifh white ; the fpines green, and reddifh at the tips. 
Another variety with Ihort but very beautiful fpines is 
almod entirely purple. This is reprefented in the en¬ 
graving at fig. 2, and one of the fpines at b. 
5. Echinus Baderi, or Bader’s fea-urchin. Shell de- 
prefled, with fewer tubercles, and a ferrate line down the 
middle of the fpaces : pores of the avenues placed in al¬ 
ternate rows of two and three foramina. Inhabits the 
European Ocean, and is principally didinguidied from 
the eiculentus, in being lefs, in having the top more de¬ 
preded, and the avenues of pores narrower. 
6. Echinus hemifphsericus. This is ftriCtly hemi¬ 
fpherical, depreded, with ten avenues of pores; the 
fpaces with a ferrate future down the middle, and tranf- 
verfe lines ; mouth pentangular; the angles obtufe. 
Probably a variety only of the efculentus. Shell yellow- 
ifh-red with paler avenues, the bafe ochraceous ; rough 
with larger and fmaller protuberances. The fpines are 
fmooth and dtort; of a reddilh colour in the living ani¬ 
mal, but after death foon turn yellow. 
7. Echinus angulofus ; hemifpherical; the fpaces gra¬ 
nulate and bifarioudy warted, the larger ones biparted by 
a ferrate future down the middle ; avenues trifarioudy 
porous. Shell grey, with a greenifh violet tinge ; fpaces 
with rows of granulations and protuberances ; avenues 
with double didant pores. There is a variety deferibed 
by Knorr, fmaller than the above, and of a light greenilh 
colour. In the middle of each dividon is a line, not per¬ 
forated with pores, but with a row of tubercles on each 
fide of it. Behind thefe rows are two lines pierced with 
a vad number of pores, and bounded by a fingle row of 
tubercles, to which joins the dentated future which con¬ 
nects the parts. The lobes themfelves condd of an infi¬ 
nite number of little fquares, each bearing at lead one 
tubercle. The mouth is pentagonal; on each lobe within 
there is a railed hook like an arched dpor, and two fur¬ 
rows belonging to each lobe at the rim of the mouth. 
The vent is at the apex, and is covered with a cartilage 
which reaches over the pentagonal perforated rim de¬ 
feribed under the fird fpecies. The fhell is thin, and 
very brittle. Another variety has been obferved with 
the apex red, and red fpots on the tubercles. But of this 
fpecies of echinus there are more than thirty varieties; 
fome either light or dark green ; others green with white 
lines, white with green lines, tranfverfely driped, or 
fpotted white or green. The prefent variety is delineated 
in the engraving at fig. 3. 
8 . Echinus excavatus: hemifpherical j fpaces granu¬ 
late, 
