The Pamphlet Collection of Sir Robert Stout: Volume 6
4. Pythonidæ, or Rock-Snakes. — Morelia. Grey. — Morelia Spilotes. The Diamond Snake
4. Pythonidæ, or Rock-Snakes.
Morelia Spilotes. The Diamond Snake.
Head shields small, scale-like; three pairs of distinct frontal plates, vertical plate indistinct, rostral shield with a pit on each side, first and second upper labials pitted; of the lower labials the first seven are smooth, then follow seven deeply pitted scales, and 3 or 4 smooth ones, nostrils lateral, in a single plate with a groove beneath; eyes lateral; pupil elliptical, erect; scales smooth; subcaudal plates in two rows, two spur-like appendages near the vent.
Bluish black above, almost every scale with a yellowish (white in spirits) elongate spot in the centre; there is a series of dark-edged irregular blotches upon the back, each bearing in the middle a few very bright yellow-colored scales; these spots or blotches vary considerably in different individuals, specimens from Port Macquarie having almost the markings of the Carpet Snake, but still retaining the yellow spot in each scale, which in page 39 M. variegata is wanting. Some specimens occur with a pale yellow streak from the side of the head to the vent: in fact we very rarely find two of these snakes which do not differ considerably in their markings.
The range of the Diamond Snake (M. spilotes) is restricted to a very limited area of country, being found in no other part of Australia than from Port Macquarie to Jervis Bay, or perhaps Cape Howe; and from the coast to the western slopes of the Blue Mountains and the Liverpool Range. In the plains watered by the Lachlan, the Murray and the Murrumbidgee, the present species is not found, the Carpet Snake (Morelia variegata) taking its place there.
The Diamond Snake is a common species in the county of Cumberland, in the Blue Mountains and the Illawarra district; it is a harmless creature, which may be picked up by any body without ever offering to bite; though it is a strictly nocturnal snake, individuals are nevertheless met with during the day-time, either basking in the sun and digesting their food, or, having been disturbed, in search of a place of shelter. Like the other species of the family Pythonidæ, they prey upon birds, and the smaller species of Mammals; young individuals feeding upon insects, frogs, or birds' eggs; the female deposits 30 or more eggs in December or January, which in a month or two the sun brings to maturity. I am not aware that the mother cares any longer about her progeny, after laying the eggs; and I have never seen or heard of a single instance where she coiled herself upon the eggs so deposited.
Diamond Snakes are found in almost every kind of country as long as it offers sufficient shelter; they prefer open stony ridges studded with low trees and well supplied with water, the edges of swamps and lagoons are frequented by them, as they find there a considerable supply of Water-rats (Hydromys), young Ducks, and other water-fowl; they also often visit the hen roosts of the farmer, or surprise "Opossums" (Phalangista) or "Flying Squirrels" (Petaurus), upon the branches of high Eucalypti.
The largest specimen, to my knowledge, that has been captured near Sydney, and properly measured, without being stretched, was 10 feet 3 inches long; that individuals of 11 page 40 feet or more in length occur, I doubt not, though they are very rare indeed, and have never come under my notice.
The way in which Diamond Snakes capture their prey is as follows:—
The snake suspends itself from the branch of some low bush or tree and watches for the victim, which often plays about near its unseen enemy. The reptile, with its neck and head bent into the form of an S, deliberately measures its distance, uncoiling more of its body if necessary, and often almost touching the animal it is in wait for; as soon as the snake is sure to reach its victim, it darts forward, generally catching the prey by one of the hind legs, and instantly takes a turn around its body, soon extinguishing life through its powerful pressure. As soon as the animal is quite dead, the process of swallowing begins, the snake always commencing with the head; this done, the reptile will often for days together bask in the sun, until the food is so far digested as to impede its movements no longer.
If a snake is disturbed during this state, it will almost always throw up the half digested carcass.
In a state of nature they never touch any food except living animals. I once, however, observed a Diamond Snake, which was kept in a cage, swallow a rat which had been killed by a Brown-banded snake (Hoplocephalus curtus.)
The present species is greatly infested by various kinds of Intestinal worms, including a Tape worm, clusters of which I have frequently taken from the stomach of this reptile.
Before concluding, a few remarks will be necessary with regard to the Carpet Snake (Morelia, variegata).
There is very little, if any difference in the distribution and number of scales between the Diamond and Carpet Snakes, the only character in which both snakes vary, is the coloration; the first having a yellow spot in the centre of each scale, whilst the latter has the back ornamented with numerous irregular black edged brown blotches; the belly, as in the Diamond Snake, being yellowish. I have mentioned before the remarkable fact, that the Carpet Snake is found in every part of Australia, except the Coast District, say from Cape Howe to the Hastings, and about 100 miles page 41 inland; at Port Macquarie both species occur, but at the Clarence River, according to Mr. James F. Wilcox, the Carpet Snake alone is found. Dr. J. E. Gray has indeed tried to distinguish the one from the other by the vertical plate, which he considers distinct in Morelia variegata, and indistinct in M. spilotes. But after examination of large numbers of both species, I do not think that the above is a character much to be relied upon, and I am led to believe that both Snakes are but varieties of the same species.
There is, according to Duméril and Bibron, the famous French Herpetologists, a second species of Snake of the Boa family to be found near Sydney, namely,