733 
I C H 
Saxony, and principality of Gotha: twelve miles eafl- 
fouth-eaft of Gotha. 
ICKTHYOCOL'LA, /. [Greek; from i X Svc, a fifli, 
and y.o>,\x, glue.] Isinglass ; a preparation from the air- 
bladders of the cod-fifli, fturgeon, and fome others. For 
the methods of preparing it, fee the article Fishery, 
vol. ,vii. p. 4.17. and Gadus, vol. viii. p. 156. When pro¬ 
perly made, it is one of the fineft of the animal glues, and 
without Buell or tafte. When beat into ill reds it readily 
diiiblves in water or milk, forming a mild, nutritious, 
reiterative, aliment; as well as a remedy in the fluor al- 
bus, continued diarrhoeas, and other evacuations from de¬ 
bility. Its folution in water or fpirit, if nicely fpread 
upon filk, is an elegant plafter for the flighted injuries to 
the tkin; and, joined with fome refins, it is called court- 
plajicr. It is faid to agree with the gum-tragacantli in 
medicinal virtues; but, like all other animal mucilages, 
jit Toon runs into a ftate of putrefaction, and becomes 
more irritating than the vegetable mucilages. Hollow 
cylinders of ilinglafs are employed to fupport the fides 
of a divided inteftine, when united by a future : a palfage 
is thus left for the contents, which by a folution of the 
ifinglafs is gradually enlarged till the wound is healed. 
ICHTHYOLI'THUS, f. [from «y 0 u?,.a fifli,' and AiOcc, 
a hone.] In mineralogy, a genus of petrifactions, cqnlift- 
ing of the body or parts of a fifli changed into a foflil 
fubftance. 
1. Ichthyolithus niger 1 in a black flaty hone. Found 
in a black date in the illand of Sheppey, and various parts 
of Wales; alfo in the mountains of Swifferland, Silefia, 
Germany, &c. impregnated with bitumen, pyritaceous 
matter, or oxyd of copper. The fifhes themfelves relem- 
ble the eel, fword-fifh, cod, flat-fifh, perch, roach, dace, 
mackaiel, mullet, carp, tench, pipe-fifh, ray, &c. 
2. Ichthyolithus albidus: in a pale flaty hone. Found 
in various parts of England ; on Mount Libanus in Pa- 
lehine ; in the ecclefialtical territories of Italy ; in Swif¬ 
ferland, Bavaria, &c., The fiflies are rarely of the lea-kind, 
as flat-fifh, mackarel, gurnard, &c. but ufually of the f'refti- 
,water kind, as eels, perch, tench, dace, roach, ialinon, 
Sec. They are feldom found whole, but in different parts, 
as the head, gill-covers, and other bones, fins, tails, ten¬ 
drils, or fcales. 
3. Ichthyolithus bufonites, or toadhone. The grinders 
of the fea-wolf, commonly called taadjlones, are found in 
various parts of England, particularly in Oxfordlhire; 
generally roundifh and hollowed like a cup, from the fize 
of afmall pea to nearly an inch in diameter; colour black, 
grey, or brown, fometimes finely variegated, always po- 
iiflied. 
4. Ichthyolithus gloffopetra : the teeth of the fliark. 
Thefe have; been found in various parts of England and 
Scotland; in Malta, Italy, France, Germany, See. of va¬ 
rious fizes, folitary or many together, loole or attached 
fo other foflils, fibrous internally, filming outwardly ; 
colour bay or dark brown, fometimes glaucous -or fea- 
green. 
ICHTHYOL'OGIST, f [from ichthyology .] A writer 
upon fiflies; a deferiber-of fifhes. 
ICHTHYOL'OGY, J. [of <^ 0 ^, a fifh, and Xoyo;, a 
difeourfe.] A treatife upon fiflies; that department of 
zoology which comprehends the clafTification and delcrip- 
tion of fiflies. 
Among animated beings, there are two very numerous 
clafles, the firft of which claim the air for their abode, 
the fecond the floods; but which, by the apparent contrafts 
in their habits, yet the fecret analogies which combine their 
motions, are calculated rather than any others to unfold to 
us certain views of that wonderful collection of relations 
and connections which are derived from the firft law of na¬ 
ture. We will therefore compare them together, and ex¬ 
hibit their principal features in the fame picture. 
Swimming and flying may be confidered as the fame 
act performed in fluids of a different nature. The inftrU' 
Vol. X. No. 708. 
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menta which effect them, the organs which facilitate them, 
the motions by which they are produced, accelerated, 
retarded, or directed, the obftacles by which they are di- 
minifhed, turned afide, or fufpemled, are fimilar or ana¬ 
logous; and, after this general and remarkable agreement, 
we fliall not be furprifed at thofe fecondary analogies which 
we may meet with between the habits of birds and thofe 
of fiflies. 
The wing of the bird and the fin of the fifli differ much 
lefs than at firft fight may be fnppofed ; and hence it is 
that the fame word lias been uled to defignate them in. 
feveral languages. Each prefents a large furface in com- 
parifon to the fize of the body, which furface the animal 
can increafe or diminifli at will, either by forcibly ltrefching 
it out, or by drawing it into folds or pi hits. The fin, like 
the wing, is fubjeCt to thefe different difplays, becaule, 
like the wing, it confifts of a membranous fubftance, foft 
and pliable; and, when it has received the dimenfioncon* 
fonant to the immediate will of the animal, it prefents, 
like the wing, a refifting furface; it acts with precifion, 
and ftrikes with force, bccaufe, equally with the inftru- 
ment of flying, it is fuftained by little cylinders, regular 
or irregular, folid, hard, almolt inflexible ; and, if not de¬ 
fended by feathers, it is fometimes ftrengthened by fcales, 
which are of a fimilar confiftence. The fpecific weight 
of birds is very nearly that of the air ; that of fiflies is 
ftill nearer to the weight of water, and efpecially of fea- 
water. 
The organization of birds is calculated to unite a large 
Tize with the leaft weight; their lungs are very much ex¬ 
tended ; they have large air-bladders ; their bones are 
hollowed and perforated fo as eafily to admit the atmof- 
pheric fluids into their cavities. Fifhes have moftly a pe¬ 
culiar bladder, which it is in their power to inflate, and 
thereby increafe their fuperficial volume or fize, but, in- 
ftead of increafing at the'fame time their weight, it really 
lefiens their fpecific gravity, being filled with a fluid or 
gas of extraordinary levity, as we fhall more fully explain 
farther on. 
The tail of a bird is a helm, and their wings are oars. 
—The anal and dorfal fins may alfo be compared to a 
power which governs and directs, while the tail properiy 
fo called, lengthened by the caudal fin, ftrikes the water 
like an oar, and, corihnunicaling to the whole animal the 
impulfe itlelf receives, driveait forward. 
Birds work their wings with more or lefs celerity; but, 
when they are on the full ftretch, and they wife to ufe 
them in changing their pofition, they do not give them 
two equal motions in fucceflion ; they raife them much 
flower than they drop them; they give alternately a yeiy 
ftrong and a very weak ftrolce, in order that wher. they 
afeend, for inftance, the upper current of air, being lei's 
agitated by them than the lower one, may oppofe lefs re- 
fiftance to their being borne up from beneath.—Several of 
the fins of fiflies, in like manner, frequently give equal and 
unequal ftrokes alternately ; and, if the taii ftrikes with 
equal rapidity to the right and to the left, it is from the 
equal refiftance of the iateral preffure againit which the 
animal afts obliquely, which gives it the diagonal direc¬ 
tion it naturally leeks. 
Thus we may fay that birds fwim in the air; and that 
fiflies fly in the water. The atmofphere is the lea of the 
former; the fea is the atmofphere of the latter. But fifties 
occupy their domain more fully than birds. Birds of the 
boldelt flights, fuch as the eagle, and the lpecies of Pele- 
canus called the man-of-war bird, feldom rife into the 
higher regions of the air; they never explore thofe limits 
of the ethereal regions where the rarity of the atmofphere 
would affeft their refpiration, and the coldnefsof the tem¬ 
perature would ftrike them with torpor or death. The 
neceflity of food, reft, and (belter, bring them continually 
near the earth.—Not fo the fiflies. They range perpetually 
and in every direction through the immenfity of the ocean"; 
in a fluid, which, being almolt of equal denfity and warmth 
B 4 at: 
