1M 



X'AKPUS. 



ICHTHYOSAURUa 



M 



4. CfthHmi.Ctffta deeply notched, leaving a circular aper- 

 Uire brtwrao it and the jaw. ; abdomen generally -7 jointod ; woond 



ffrnlmfit HT+TC * t * etl1 r th mandible* directed out- 

 wards, U mandibles when elo*ed not touching each other. Mr. 

 Halliday add* a. a distinct iub family the Apkidii and allied genera, 

 which have the articulation between the eoond and third abdominal 

 MfBont* flexible. Mr. Weatwood however ragardi them as a group 

 equivalent with WoHnaeTs other actions, and which it might pcrhap* 

 be man natural to arrant* either before or after the Polymorpk,, with 

 which they are united by WetmaeL 



The habiU of the /. A<l*-iti, or Braconidtt, present no broad 

 distinction from the re*t of the family. Many of the genera promt 

 poenUarities of structure, ai for instance the coalition of the dorsal 

 eegmenu of the abdomen in Ckttmtut, Siyalplna, Mitigaiter, and the 

 (raping mandible* of Atyna; the roitrated front of Agatha, and 



Alftia. 



the tTHrt-rn>- of a stigma on the front margin of the poitenor wings 

 of the male* in /iWmupiYw and fftmbottu. 



(Waatwood, Introduction to Utt Modtr* Ctaitifi cation of Ituecti.) 



ICHXUTAUITS (from lx>t, a footstep, vestige, and nifwia, a 

 fruit, in reference to the slender follicles), a genus of Plants belonging 

 to the natural order Apocynacea. It has a salver-shaped corolla, 

 (cleft calyx, and inclosed stamens ; sagittate anthers, free from the 

 stigma. The specie* are climbing shrub* with opposite leaves ; the 

 flowers in branched terminal panicles, white, and inodorous. 



l.fnUaeau has a twining stem, oblong-lanceolate leaves tapering to 

 both ends, axillary peduncle* very long and racemose. It U a native 

 of Ceylon and NepauL The flowers are small and purple ; the leaves 

 deep green above and pale beneath. According to Dr. Koyle, it is 

 o*aotinm* used in India as a substitute for sarsaparilla, and it U 

 also mentioned by Afzelius in his ' Ueniedia Quinensia,' as a medicinal 

 plant. 



/. /rayraiu has oblong lanceolate leave* tapering to both ends, and 

 axillary trichotomous spreading peduncles. It is a native of Nepaul, 

 and has large handsome flowers. 



/. A/:rlii is a glabrous shrub with twining stems, oval acute leaves 

 at the base, oblong or lanceolate as they approach the top. The 

 corollas are white and sweet-scented. It U a native of Sierra Leone, 

 and about the river Bascha, in woods and among bushes. 



/. Zoarnni has a frutescent stem, orate oblong leave*, lateral 

 3-flowered peduncles. It is a native of Zanzibar. All the specie* of 

 Idaioearptu grow well in a mixture of loam, peat, and sand, and 

 cutting* strike readily in aand under a hand-glass. 



(Don, lUeUamydeoiu I'lantt ; Lindley, Flora Medico.) 



1CHTHYOLOUY. The branch of science which comprehends a 

 knowledge of the structure, nature, and forms of Fishes is thus called. 

 The general structure and classification of Fishes U treated of in this 

 work under the head of FISH, and all the more important and British 

 genera will be found under their generic names, or the families 

 to which they belong, a* Aiiuouvriu ; UORTI-H.EXA ; CLUPELD*; 

 Boutin* 



It'MTHYoPHTHALMITE. [Ai-omrLum] 



ICHTHYOSAURUS, literally Fish-Lizard ('Irfiit : SoSpot), the 

 generic name given by Mr. Konig to the extinct fossil animal noticed 

 by the late Sir Kverard Home, under the appellation of Pmttotaurut, 

 and by Wagler under the name of (Jiyphu*. 



We are indebted to Sir Henry Ue la Heche and the Rev. W. D. Cony- 

 beare principally for pointing out and illustrating the structure of this 

 extraordinary creature; and that at a time when the materials were 

 far more scanty than they nro at the present day. Dr. Jiiger, 

 Mr. Hawkins, Dr. Buckland, Sir Philip de Mai pa* Grey Egerton, and 

 lYofeasor Owen, nave all contributed to throw light on the organisation 

 of a being that baa long ceased to exist ; and the auatomy and animal 

 economy of this tyrant of the seas of former ages is now nearly as 

 well known as that of the porpoise which revels in the ocean that 

 washes the shores of our existing continents and islands. We ought 

 also to add that we are deeply indebted for an early knowledge of the 



in* of this creature to the indefatigable exertions of a lady 

 Anning, of Lymo Regis, who diligently collected the first 

 in* of the bone* of the Jchlhyjiaurtu from the cliffs of Lyme 



" If," write* Dr. Buckland, in his ' Bridgcwator Treatise,' " we 

 examine Uwos creature* with a view to their capabilities of locomotion, 

 of offence and defence which their extraordinary 

 afforded to them, we shall find combinations of form and 

 contrivance* which are now dispersed through various 

 C!MM and orders of existing animals, but are no longer united in the 

 ame grans. Thus, in the same individual, the snout of a porpoise 

 is oombiatd with the teeth of a crocodile, the head of a lizard with the 

 vertebra of a fish, and the sternum of an Ornilhorhynchut with the 

 paddle* of a whale. The general outline of an Jchthyotaurui must 

 bare mart nearly rambled the modem porpoise and grampus. It 

 bad four broad feet or paddles, and terminated behind in a long and 

 powerful UiL Some of the largt of these reptiles must have 

 cxoxded thirty bet in length." We shall now endeavour to give a 

 fetch of the organisation of those KnalioMurian*. 



The oeteology of the head agrees in many point* with that of the 

 crocodile, but the orl-it of the eye is much larger, and the nostril is 



not, as in that genus, placed near the point of the snout, but near 

 the anterior angle of the orbit, as in same other lizards. The teeth, 

 which in some cases amount to a hundred and eighty, are not incased 

 in deep and distinct sockets as in the crocodiles, though the rudiments 

 of on alveolar separation may be traced in the small ridges between 

 the teeth running along the furrow of the maxillary bone in which 

 they are set The succession of teeth is managed much after the same 

 manner as that which obtains in the crocodiles [CIIOCODIUD.K], the 

 young tooth budding up at the base of the old tooth, where, as it 

 grows, its lateral pressure sets the absorbents at work ; the base of 

 the old tooth is thus partially removed, and, as the new tooth 

 advances, is finally displaced to make room for its more efficient 

 successor. The elongated jaws in which these instruments of destruc- 

 tion ore arranged are made up, as in many of the crocodile* and the 

 other lizards, of many thin bony plates, so as to produce a onion of 

 lightness, elasticity, and strength. " It is obvious," says Dr. Buckland, 

 in the interesting work above quoted, " thnt an under jaw so .-1 

 and so much elongated aj that of a Crocodile or Icltthyosaunu, and 

 employed in seizing and retaining the large and powerful animals 

 which formed their prey, would have been comparatively weak and 

 liable to fracture if composed of a single bone. Each side of the lower 

 jaw was therefore made up of six separate pieces, set together in a 

 in inner which will be best understood by a reference to the figure*. 

 This contrivance in the lower jaw to combine the greatest elasticity 

 and strength with the smallest weight of materials, is similar to that 

 adopted iu binding together several parallel plates of elastic wood or 

 steel to make a crossbow; and also in setting together thin plates of 

 steel in the springs of carriages. A* iu the carriage-spring or com- 

 pound-bow, so also in the compound-jaw of the Jchthyotaurut, the 

 plates are most numerous and strong at the parts where the greatest 

 strength is required to be exerted ; and are thinner and fewer towards 

 the extremities, where the service to be performed is less severe. 

 Those who have witnessed the shock given to the head of a crocodile 

 by the act of snapping together its thin long jaws, must have seen 

 how liable to fracture the lower jaw would be were it composed of 

 one bone only on each side : a similar inconvenience would have 

 attended the same simplicity of structure in the jaw of the Ichtkyo- 

 taunts. In each cose therefore the splicing and bracing together of six 

 thin flat bones of unequal length and of varying thickness, on both 

 sides of the lower jaw, affords a compensation for the weakness and 

 risk of fracture that would otherwise have attended the elongation of 

 the snout. Mr. Conybeare points out a further beautiful contrivance 

 in the lower jaw of the Jchthyoiaurtu, analogous to the cross-bracings 

 lately introduced in naval architecture." 



Hitherto the structure of the skeleton of the Ichthyosaurus is, as 

 we have seen, sauroid ; but we now come to a part of its bony frame, 

 and a very principal part, which is formed on the ichthyoid or fishy 

 type. The vertebral column, consisting of more than one hundred 

 vertebra;, each of which is hollow and fashioned after the manner of 

 those of fishes, to facilitate the progress of the animal through the 

 watery medium in which it existed, is constructed for a swimming, 

 not a walking animal ; and the sauroid type is here departed from in 

 favour of a conformation demanded by the habits of the animal. A 

 peculiarity in this part of the structure is noticed by Sir E. Home, 

 the annular part of the vertebra being neither consolidated with its 

 body, as in quadrupeds, nor connected by a suture, as in crocodiles; 

 but remaining always distinct, and articulating by a peculiar joint, 

 resembling a compressed oval ball-and-socket joint. Mr. Conybeare 

 observes, in addition, that this mode of articulation co-operates with 

 the cup-shaped form of the intervertebral joints in giving flexibility 

 to the vertebral column, and assisting its vibratory motions ; for had 

 these parts been consolidated, as iu quadrupeds, their articulating 

 processes must have locked the whole column together, so as to 

 render such a motion of its parts impossible ; but by means of this 

 joint every port yields to that motion. (Hucklaml, 'Bridgewater 

 Treatise.') 



Sir Philip Egerton, in his paper ' On Certain Peculiarities in the 

 Cervical Vertebra: of the Ichthyosaurus, hitherto unnoticed ' (' Qeol. 

 Trans.,' 1836), has demonstrated that the first and second c 

 vertebra) (in some species at least) ore anchylosed ; and he further 

 notices a very remarkable feature which at once distinguishes these 

 vertebra from the other bones of the spinal column. He shows that 

 on the under surface of each bone there exists an unusual enlarge- 

 ment in the form of a solid wedge-shaped process, placed transversely 

 to the smaller diameter of the vertebra;. By this arrangement four 

 triangular planes are produced. " The first and largest is baaed upon 

 the lower anterior margin of the atlant&l socket, having its apex 

 directed downwards and backwards until it meets the apex of a 

 similarly-shaped though smaller plane proceeding downwards and 

 forwards from the posterior margin of the atlas. The third, of like 

 shape and size with the second, extends from the anterior margin of 

 the axis, and joins the apex of the fourth, which inclines forwards 

 from the posterior portion of the name bone. This fourth plane is 

 considerably smaller than the others, and corresponds in siz 3 with a 

 fifth, placed on the anterior border of the third cervical vertebra. 

 When therefore the three anterior vcrtebnc are in their natural 

 position the arrangement of the five planes is as follows : the first 

 and largest occupies the lower front of the atlas; the second and 



