93 



OPHIDIA. 



OPHIDIA, 



backwards ; and the greater number have only one very long lung, 

 with the veatige of a second. These serpents, says Cuvier, in continu- 

 ation, are divided into venomous and non-venomous ; and the former 

 are subdivided into venomous with many maxillary teeth, and 

 venomous with isolated fangs. In the non-venomous, the branches of 

 the upper jaws are furnished throughout their length, as well aa those 

 of the lower jaw and of the palatine branches, with fixed teeth which 

 are not pierced : there are therefore four nearly equal rows of these 

 teeth in the upper part of the mouth, and two in the lower. [BoiD.fi.] 

 Those which have the mastoidian bones comprised in the cranium, the 

 orbit incomplete backwards, and the tongue thick and short, much 

 resemble the Amphubutnidie in the cylindrical form of their head and 

 body, and have, Cuvier observes, been united to the Orvets [OBVET], 

 in consequence of the smallness of their scales. 



The Venomous Serpents with isolated fangs present a very peculiar 

 structure in their organs of manducation. Their superior maxillary 

 bones are very small, carried on a long pedicle analogous to the 

 external pterygoid apophysis of the sphenoid bone, and very move- 

 able : here is fixed a pointed tooth, pierced with a small canal which 

 gives icsue to a liquor secreted by a considerable gland situated under 

 the eye. It is this liquor which, when shed into the wound made by 

 the bite of the serpent, carries havock into the body of the wounded 

 animal, and produces effects more or less fatal according to the species 

 which has inflicted the wound. This fang is concealed in a fold of the 

 gum when the serpent does not wish to use it ; and there are behind 

 it many germs destined to fix themselves in their turn, in order to 

 replace it if it should be broken in the wound it makes. Naturalists, 

 Cuvier remarks, have named these teeth crochets mobiles, or moveable 

 fangs ; but it iv properly speaking, the maxillary bone that moves : 

 that bone carries no other teeth, fo that, in the Venomous Serpents, 

 only two rows of palatine teeth are seen hi the roof of the mouth. 

 All the venomous species bring forth their young nlive, in consequence 

 of the egg being hatched internally before it is laid, whenco their 

 general name of Vipers, a contraction of Viviparet. 



These deadly serpents with isolated fangs, though they present 

 external characters of the same nature as the preceding group, have, 

 the greater number of them at least, very dilatable jaws and a very 

 extensible tongue. Their head, wide behind, has generally a ferocious 

 aspect, which announces in some degree their malevolent nature. 



[Vll'EIllD.K.] 



A third tribe baa the jaws organised and armed nearly an in the 

 Non-Venomous Serpents, but the species have the first of their 

 maxillary teeth greater than the others, and pierced so as to conduct 

 the venom in the same manner as is effected in the Venomous Serpents 

 with isolated fangs. Such are the Jlunyari and Hydri. [HYDRIDE ; 

 I'EI.AIITS.] 



The serpent*, with one exception (Deirodon, to which we shall pre- 

 sently more particularly call attention), subsist on living prey ; and, 

 whether non-venouious or venomous, have their teeth, as might be 

 expected, admirably constructed and arranged for the purpose of 

 securing their prey and assisting in deglutition. 



Professor Owen, in his valuable and copiously-illustrated ' Odonto- 

 graphy,' observes that the order Ophidia, as it is characterised in the 

 system of Cuvier, requires to be divided into two sections according to 

 the nature of the food and the consequent modification of the jaws and 

 teeth. Certain species, he observes, which subsist on worms, insects, 

 and other small invertebrate animals, have the tympanic pedicle of the 

 lower jaw immediately and immoveably articulated to the walls of the 

 cranium ; the lateral branches of the lower jaw are fixed together at 

 the syraphysis, and are opposed by the usual vertical movement to a 

 similarly complete maxillary arch above : these, as we have above 

 seen, belong to the genera Amphisbama and Anyv.it, Linn. The rest 

 of the Ophidians, observes the Professor, which form the typical 

 members, and by far the greatest proportion of the order, prey upon 

 living animals, frequently of much greater diameter than their own ; 

 MV\ the maxillary apparatus is, as we have also above seen, conform- 

 ably and peculiarly modified to permit of the requisite distention of 

 the soft parts surrounding the mouth, and the transmission of the prey 

 to the digestive cavity. 



J'-ut the mechanism by means of which this distension is accom- 

 plished, and which is in fact a dislocation of adapted parts which 

 return to their original positions when the act of deglutition is accom- 

 plished, requires, to be well understood, a more particular description 

 than the general account above given, and we proceed to that presented 

 by Professor Owen, as the best and clearest known to us. 



The two superior maxillary bones have, he observes, their anterior 



extremities joined by an elastic and yielding fibrous tissue with the 



small and single intermaxillary bone : the symphysial extremities of 



tlic lower maxillary rami are connecter! together by a similar tissue, 



allowing of a still wider lateral separation. The opposite or posterior 



extremity of each ramus is articulated to a long and moveable vertical 



pedicle formed by the tympanic or quadrate bone, which is itself 



attache'! to the extremity of a hori/xintal jiedicle formed by the mastoid 



, *o connected as also to allow of a certain yielding movement 



the cranium. The palatine and pterygoid bones have similarly 



loose and moveable articulations, and concur with the. other denti- 



"H of the mouth in yielding to the pressure of large bodies 



with which the teeth may have grappled. 



Professor Owen first describes the dental' peculiarities of the true 

 serpents, which, as he remarks, swallow their food whole, whether 

 they prey on living animals, as is the case in almost every species, or 

 feed on the eggs of birds, as does Deirodon scaber, Oweu (Coluber scaber, 

 Linn.) With the exception of this and some congeneric species, in 

 which the teeth of the ordinary bones of the mouth are so minute as 

 to have been deemed wanting, the maxillary and premandibular bones 

 in all true Ophidians are, he observes, formidably armed with sharp 

 pointed teeth ; there is on each side of the palate a row of similar teeth 

 supported by the palatine and pterygoid bones : in the great Pythons 

 and some species of Boa, he adds, the intermaxillary bone also supports 

 teeth. But whatever be their position, all the teeth, according to the 

 Professor, present a simple conical form, tbe cone being long, slender, 

 and terminated by an acute apex, and the tooth is either straight, or 

 more commonly bent a little beyond the base, or simply recurved, or 

 with a slight sigmoid inflection. Thus the teeth are adapted for 

 piercing, tearing, and holding, not for dividing or bruising. Certain 

 teeth in some species are traversed by a longitudinal groove, as above 

 noticed, for conveying an acrid saliva into the wounds which they 

 inflict ; in others, two or more teeth are longitudinally perforated for 

 transmitting venom. These poison-fangs, he remarks, are always con- 

 fined to the superior maxillaries, as we have already stated, and are 

 generally placed near the anterior extremity of those bones. 



Professor Owen notices in the first instance the serpents whose teeth 

 are all simple and .-olid, where the pulp which occupies the basal 

 cavity is calcified. 



After this the teeth of the poisonous serpents are described, and 1'ro- 

 fessor Owen calls attention to the fact that in certain genera of non- 

 venomous serpents, as in Dryophig, Dipsat, and Bucephalus, in which 

 the superior maxillary teeth increase in size towards the posterior part 

 of the bone, the large terminal teeth of the series are traversed along 

 their anterior and convex side by a longitudinal groove. In the Jiu- 

 ce]Jialu8 Capensis the two or three posterior maxillary teeth present 

 this structure, and are much larger than the anterior teeth or those 

 of the palatine or premandibular series ; they add materially there- 

 fore, he observes, to the power of retaining the prey, and may conduct 

 into the wounds which they inflict an acrid saliva, but they are not in 

 connection with the duct of an express poison-gland. The long grooved 

 fangs are either firmly fixed to the maxillary bones, or are slightly 

 moveable, according to their period of growth ; they are concealed by 

 a sheath of thick and soft gum, and their points are directed back- 

 wards. The sheath also contains loose recumbent grooved teeth, ready 

 to succeed those in place. 



In most of the Colubers each maxillary and premandibular bone 

 includes from 20 to 25 teeth : they are less numerous in the genera 

 Tortrij; and Ilomalopeis, and are reduced to a still smaller number iu 

 the poisonous serpents, in the typical genera of which the short 

 maxillary bone supports only a single perforated fang. 



The transition to the poisonous serpents, which was begun iu the 

 Ilui-'l>ha/i and allied genera with grooved maxillary teeth, is, according 

 to Professor Owen, completed by the poisonous serpents of the genera 

 Pelaviyt, JJydrophis, Elapi, Bungarus, and llamadrgtu, which latter 

 genus, as its cervical integument can be expanded into a hood, con- 

 stitutes an immediate link between the Bitnyarus and Naja. 



The structure of the venom-fangs of serpents, and the machinery 

 by which their deadly agency is brought to bear against those who 

 are so unfortunate as to be the objects of their attacks, are so inter- 

 esting, that we subjoin the following remarks in the author's own 

 words : 



"The superior maxillary bone diminishes in length with the 

 decreasing number of teeth which it supports. The transverse or 

 external pterygoid bone elongates in the same ratio, so as to retain its 

 position as an abutment against the shortened maxillary, and the 

 muscles implanted into this external pterygoid style communicate 

 through it to the maxillary bone the hinge-like movements backwards 

 and forwards upon the ginglymoid articulations, connecting that bone 

 with the anterior frontal and palatine bones. As the fully-developed 

 poison-fangs are attached by the same firm basal anchylosis to shallow 

 maxillary sockets, which forms the characteristic mode of attachment 

 of the simple or solid teeth, they necessarily follow all the movements 

 of the superior maxillary bone ; when the external pterygoid is 

 retracted, the superior maxillary rotates backwards, and the poison- 

 fang is concealed in the lax mucous gum, with its point turned back- 

 wards : when the muscles draw forward the external pterygoid, the 

 superior maxillary bone is pushed forwards, and the recumbent faug 

 withdrawn from its concealment and erected. 



" In this power of changing the direction of a large tooth, so that 

 it may not impede the passage of food through the mouth, we may 

 perceive an analogy between the Viper and the Lophius; but in the 

 fish the movement is confined to the tooth alone, and is dependent on 

 the mere physical property, of the elastic medium of attachment. In 

 the serpent the tooth has no independent motion, but rotates with the 

 jaw, whose movements ore governed by muscular actions. In the fish 

 the great teeth aro erect, except when pressed down by some extra- 

 neous force ; iu the serpent the habitual position of the fang is the 

 recumbent one, and its erection takes place only when the envenomed 

 blow is to be struck. 



"The peculiar structure of the poison-fang was first described by 



