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The Pamphlet Collection of Sir Robert Stout: Volume 6

Ophidian Reptiles. — Ophidia—Snakes

Ophidian Reptiles.

Ophidia—Snakes.

The geographical distribution of snakes is very extensive. They inhabit almost every country from the south of Sweden and Siberia to Tasmania, None have as yet been recorded from New Zealand. India, America, and tropical Africa, appear to be the strongholds of the highly venomous species; and in these countries the dangerous Rattlesnakes, Copper-heads, Puff Adders, and Lance-heads, are met with—all of which have very long movable fangs, and belong to genera which are not found in Australia. Only five species are dangerous to man when full grown—the Black Snake (Pseudechis porphyriacus), the Brown Snake (Diemenia superciliosa), the Brown-banded snake (Hoplocephalus curtus), the Broadscaled Snake (Hoplocephalus superbus), and the Death Adder (Acanthopis antarctica); all these retire under ground during the cold season, only a few young specimens being found under stones.

Our Death Adder is the nearest approach to the Viper, but its fangs are permanently erect, and its bite is not nearly so dangerous as that of the above-mentioned species. It is only found in the warmer parts of Australia, and not in Tasmania, South Victoria, or South-west Australia.

Only three species of snakes inhabit Tasmania, though foreign naturalists enumerate many more. Tasmanians distinguish the "Diamond Snake" (Hoplocephalus superbus), the "Carpet Snake," and "Black Snake," (Hoplocephalus curtus), and the "Whip Snake" (Hoplocephalus coronoidcs). The first is identical with the Continental Hoplocephalus superbus. The second two are varieties of each other.; the young brought forth differing greatly in colour even in the same litter. The dark variety has been described as Hoplocephalus fuscus by M. Steindachner; but Mr. George Masters captured a large number of both kinds of snakes in Tasmania, and took from a gravid female, thirty-five young, seventeen of which were banded, and of a light colour, and the rest black.

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The third Tasmanian snake is very small, only about 16 or 20 inches long, and, though venomous, not dangerous. This reptile is known as the Whip Snake (Hoplocephalus coronoides), and is allied to the New South Wales Black-bellied Snake (Hoplocephalus signatus), and to Masters' snake (Hoplocephalus mastersii) of South Australia.

We do not know exactly how many snakes Victoria produces. In the South, the Tiger Snake (Hoplocephalus curtus) and the Tasmanian Diamond Snake (Hoplocephalus superbus) are met with; also the little Black-bellied Snake (Hoplocephalus signatus) and the Black Snake (Pseudechis porphyriacus). Near the New South Wales boundary, on the Murray, we find, in addition, the Death Adder (Acanthophis antarctica), the Green-bellied or Grey Snake (Diemenia reticulata), the Brown Snake (Diemenia superciliosa), and probably also the innocuous Green Tree Snake (Dendrophis punctulata), and the Carpet Snake (Morelia variegata).

There occur in South Australia, in addition to the above, several small venomous Ophidians; the Death Adder is, however, very scarce, and, further west, altogether absent. Near King George's Sound are found many snakes of the brown-banded species, of a very marked colour, and with the bands much more distinct than in eastern specimens; small Hoplocephali, and particularly Hoplocephalus coronoides, abound on the barren hills near the Sound, but of the Ophidio-fauna further to the north-west our knowledge is limited.

Returning to New South Wales, we observe, in addition to the specimens enumerated from Victoria, the Diamond Snake (Morelia spilotes), and the Brown Tree Snake (Dipsas fusca), but miss the Tasmanian Diamond Snake (Hoplocephalus superbus). There is also a goodly number of small Ophidian reptiles, which will be fully described hereafter. Near the Queensland boundary, in the Clarence and Richmond River District, a new form has been discovered which differs from other Australian venomous species in having scales strongly keeled; this species has been described as Tropidechis carinata. A small ringed snake, with a very short head and tail, belonging to the South American genus Brachyurophis, is met with on the Clarence, as also are many other diminutive Ophidians which do not inhabit the southern districts. There the Diamond Snake disappears, and the sombre-coloured Carpet Snake takes its place, but no other Rock Snake is observed until the tropics are fairly entered.

Northern Queensland is rich in harmless Pythons; Nardoa gilbertii and Aspidiotes melanocephalus occur near Port Denison, and at the Gulf of Carpentaria two species of the genus Liasis have been observed. The harmless Fresh-water Snakes (Cerberus australis and Myron richardsonii) appear to be restricted in their habitat to the northern rivers.

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A second harmless Tree Snake (Dendrophis calligastra) has lately been discovered near Cape York, and a variety of the Australian Brown Tree Snake (Dipsas fusca) extends even to New Ireland. This large island produces a second Tree Snake belonging to the genus Dendrophis, probably a new species, and a Python (Liasis amethystinus) which grows to a considerable size. The islands to the south-east of the Solomon Group are inhabited by harmless Pythons only. Enygrus bibronii is the most common of them, and found on the Solomon, New Hebrides, and Fiji Group, and the rearer Bolyeria multicarinata, which is generally but erroneously recorded by Foreign naturalists as inhabiting the shores of Port Jackson, must also be referred to the islands east of New Guinea.

A small venomous snake, allied to the Australian genus Dieme-nia, is peculiar to Viti Levu, the principal island of the Fijis; two other venomous species have been discovered at the Solomon Islands, but no large or dangerous venomous snake is on record from any other locality in the South Pacific. At New Caledonia, snakes have not been noticed; they are also absent from New Zealand, where a few lizards and frogs represent the reptilio fauna.

Twenty-one innocuous and forty-two venomous Australian snakes have been described, but of the latter not more than five species are dangerous to man or the larger animals, and these retire under ground for nearly five months in the year. It is, of course, most desirable to distinguish the dangerous from the harmless species by external characters; and, by a little attention to the subject, this may be easily done.*

An Australian snake that is not thicker than a man's little finger, whatever may be its length, cannot by its bite endanger the life of an adult human being.

Günther states that "poisonous snakes are armed with a long canaliculated tooth in front of the upper jaw, with a duct which carries the poisonous fluid from a large gland to the tooth. This venom-gland corresponds with the parotid salivary gland of the mammals, and is situated on the side of the head, above the angle of the mouth; it is invested by a dense fibrous sheath, which is covered by a layer of muscular fibres. At the moment the snake opens its mouth to bite, these muscles compress the gland, and force its contents through the excretory duct into the channel of the venom-tooth, whence it is injected into the wound. The structure of the venom-tooth is not the same in all poisonous snakes; in some it is fixed to the maxillary-bone, which is as long, or nearly as long, as in the non-venomous snakes, and generally bears one or more ordinary teeth on its hinder portion. The page 52 venom-tooth is fixed more or less erect, is not very long, and its channel is generally visible as an external groove. The poisonous snakes with this dentition have externally a more or less striking resemblance to the non-venomous ones; and on this account they are designated as venomous Colubrine Snakes, and form the second sub-order of snakes." All our Australian venomous serpents belong to this sub-order (except the "Death Adder," Acanthophis antarctica, which occupies an intermediate position between the venomous Colubrine Snakes and the venomous snakes properly so called).

Australia has few Ophidian genera, when compared with other countries in the same latitude. The four Blind Snakes, two Colubrides, two Fresh-water Snakes, and three Tree Snakes, are not peculiarly Australian; while the six species of Bock Snakes are not found beyond this region—that is, not in India or the Islands of the Archipelago;—Timor, New Ireland, and the Fiji Group, being the extreme northern limits of the geographical distribution. Twenty-three species constitute the whole of the Australian non-venomous snakes; and, not counting the Blind Snakes, we have but five harmless Ophidians in New South "Wales. The second suborder, comprising the venomous Colubrine Snakes, is, however, very large; and forty-two well-defined Australian species are known at present. Nearly all the larger kinds have the power of dilating the skin of the neck, and resemble in this respect the Hooded Snakes or "Najas" of India. The Brown-banded Snake (Hoplocephalus curtus), the large-scaled Snake (Hoplocephalus superbus), the Black Snake (Pseudechis porphyriacus), and the Orange-bellied Snake (Pseudechis australis), belong to this group, and are perhaps our most dangerous Ophidians. Two other large snakes—the Brown Snake (Diemenia superciliosa) and the Northern Banded Snake (Pseudonaja nuchalis)—and all the small venomous but not dangerous species, do not distend their necks when angry, and probably bear a close resemblance to the Elapidæ of South America. The whole are peculiar to the Australian region, except the Short-tailed Snake (Brachyurophis australis), which, according to Günther, belongs to an American genus. The real position of the Death Adder (Acanthophis antarctica) has not yet been pointed out; in form a true viper, this snake has its poison fangs permanently erect, and will therefore be classified according to its dentition with the Elapidæ. From late experiments it also appears that the venom of this reptile is less dangerous than that of the first-mentioned four species; thus, a Frog (Hyla aurea) and a young Sleeping-lizard (Cyclodus gigas), severely bitten by a Death Adder, lived for more than twelve hours after the bite. The snake was fresh, and very vigorous, and the fangs were left in the wound for two minutes.

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It will be necessary also to say a few words about the Sea Serpents which visit our coast, as they belong to the second sub-order, and are frequently overlooked in adding up the Australian fauna.

Two well-known forms—the Ringed Sea Snake (Platurus laticaudatus) and the Yellow-bellied Sea Snake (Pelamis bicolor)—are occasionally thrown ashore on the coast of New South Wales; but eight other species have been noticed further north. Sea Snakes are rare in collections; and, in arranging the riches of the Australian Museum, one of these aquatic reptiles has been found that cannot be classed with other known forms, and will constitute the type of the new genus Emydocephalus.

We arrange the Ophidian order as follows:—

* See Krefft's Snakes of Australia, page 10.