I C H 



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ICO 



scopic and telescopic properties/' The 

 beak was that of the porpoise ; the teeth, 

 as before mentioned, those of the croco- 

 dile ; the vertebrae nearly resembled those 

 of the shark, being hour-glass shaped ; 

 the vertebral column was composed of 

 more than one hundred pieces; the ribs 

 were slender, and the majority of them 

 bifurcated, or forked, at the top ; the 

 boner, of the sternum were strong and 

 largely developed, and combined nearly 

 in the same manner as in the ornithoryn- 

 chus or platypus. The ichthyosaurus 

 had four paddles, the form of its ex- 

 tremities deviating from the saurians and 

 approaching the mammalians, being con- 

 verted from feet into fins ; these fins, or 

 paddles, were composed of numerous 

 bones enclosed in one fold of integument ; 

 the fore-paddle was composed of nearly 

 one hundred bones, and like the mam- 

 malians it possessed a humerus, or 

 shoulder bone, a radius and ulna, or the 

 bones of the fore arm, and phalanges ; the 

 bones of the phalanges were polygonal 

 and exceedingly numerous, as before 

 stated. The hind-paddles were very 

 much smaller, containing only from thirty 

 to forty bones. The general conforma- 

 tion of the ichthyosaurus must have 

 greatly resembled that of the porpoise or 

 grampus. Its teeth would have suffici- 

 ently proved it to have been carnivorous, 

 but the subsequent discovery of its faecal 

 remains, now called coprolites, and the 

 finding within the intestinal canal the 

 half-digested remains of fishes and rep- 

 tiles, render this point quite certain ; 

 like the crocodile, it must have gorged its 

 prey entire ; its stomach was exceedingly 

 capacious, forming a sort of pouch, or 

 sac, and extending through nearly the 

 whole body. The fossil remains of the 

 ichthyosaurus have been discovered in 

 the lias formation, and it appears to have 

 become extinct at the termination of the 

 secondary series of geological formations. 

 It is however 'the opinion of Mr. Bake- 

 well that the ichthyosaurus, or some spe- 

 cies of a similar genus, is still existing in 

 the present seas, and with his remarks 

 the description of the fish-like lizard will 

 be concluded. "About sixteen years since, 

 a large animal was seen for several sum- 

 mers in the Atlantic, near the coast of 

 the United States, and was called the 

 great sea-serpent. I am informed by 

 Professor Silliman, that many persons 

 who attested the existence of the sea ser- 

 pent from their own observations, were so 

 highly respectable, both for intelligence 

 and veracity, that their evidence could 

 not be disputed. I remember one of the 

 most particular descriptions of the sea- 

 serpent was given by an American cap- 



tain, who saw the animal raise a large 

 portion of its body from the water : he 

 represented it as of great length, and 

 about the bulk of a large water cask ; it 

 had paddles somewhat like a turtle, and 

 enormous jaws like the crocodile. This 

 desci'iption certainly approaches to, or 

 may be said to correspond with, the ich- 

 thyosaurus, of which animal the captain 

 had probably never heard." BakeweW* 

 Introduction to Geology. 



ICHTHYOPHTHA'LMITE. (from t%^> anc * 

 600a\/zoc., Gr.) Fish-eye stone ; apo- 

 phyllite ; pyramidal zeolite ; the fischau- 

 genstein of Werner ; mesotype epointee 

 of Hauy. It is of a white colour, and 

 semi-transparent, or translucent. Occurs 

 both crystallized, and massive. The 

 primitive form of its crystals is a four- 

 sided prism, with rectangular bases. It 

 is easily divisible by percussion into la- 

 minae, whose broader surfaces are splen- 

 dent and somewhat pearly. It scarcely 

 scratches glass, and does not yield sparks 

 when struck with steel. Specific gravity 

 2 '4 6. Before the blow-pipe it exfoliates, 

 froths, and eventually melts into an 

 opaque bead. It is composed of silica 

 50, lime 23, potash 4, water 18, with a 

 trace of fluoric acid. It is found in 

 secondary trap -rocks in the Hebrides and 

 other parts of Scotland, in Sweden, and 

 Iceland. 



I'cius. The terminations of adjectives in 

 icius and aceus express a resemblance to 

 a material ; those in eus indicate the ma- 

 terial itself: thus, membranaceus, resem- 

 bling skin ; membraneus, skin itself ; co- 

 riaceous, leathery ; latericius, resembling 

 bricks. 



ICOSAHE'DRAL. (from icosahedrsn.) Hav- 

 ing twenty equal sides or faces. 



ICOSAHE'DRON. (eiKoaafdpog, Gr. icosae- 

 dre, FT. isosaedro, It.) A regular solid, 

 consisting of twenty triangular pyramids, 

 whose vertices meet in the centre of a 

 sphere supposed to circumscribe it ; and 

 therefore have their height and bases 

 equal : wherefore the solidity of one of 

 these pyramids multiplied by twenty, the 

 number of bases, gives the solid contents 

 of the icosahedron. 



ICOSA'NBRIAN. (from eicoo'i and ai'rjp, 

 Gr.) The twelfth class in Linnaeus' 

 sexual method, consisting of plants with 

 hermaphrodite flowers, furnished with 

 twenty or more stamens, inserted into the 

 calyx. The first order of this class con- 

 sists of trees bearing for the most part 

 stone fruits, surrounded by a pulp, as the 

 plum, peach, cherry, &c. ; in the second 

 order we find the apple, pear, &c. ; in the 

 third order, the genus rosae. In this class 

 the stamens grow out of the sides of the 

 calyx, as in the strawberry, and it is im- 



