Fig. 63.—A. Lithobius forficatus. B. Mouth parts seen from below (After Graber.)
Lithobius, he tells us, lays but few eggs compared with the number deposited by Julus. Each egg, as it leaves the oviduct, is received by the hooks mentioned above, and by means of them it is rolled on the soil till a covering of earth adheres to the viscous material with which the egg is coated. The male considers the eggs special delicacies, and devours them whenever he has the opportunity. It is to prevent this that the female covers them with earth, so that the male may not recognize them.
Geophilus is a much longer animal than Lithobius, for its body may consist of from 80 to 180 rings. The species have no eyes. Several of them are common, especially in the south of England, and possess, as do many genera of the same family, the property of phosphorescence, whence have arisen the stories of ‘luminous earthworms’ current from time to time. Geophilus crassipes is the form most frequently captured when displaying its light. It is from one inch to two inches long, of a reddish-orange colour, and somewhat worm-like in shape. Mr. Pocock, of the British Museum (Natural History), says: ‘The property of luminosity lies in an adhesive fluid secreted by glands which open upon the lower surface of the body, and the power of discharging or retaining the fluid appears to be entirely under the centipede’s control. The phenomenon is observable during the autumn months, from about the middle of September to the end of November, and although its significance is not clearly understood, it is generally believed to be connected with the pairing of the sexes[40].’
During a visit to the seaside it is well to look out for specimens of a marine Centipede, which is, apparently, not very common. It is said to occur ‘under stones and sea-weeds on the shore at or near Plymouth’; and in 1895 I had the good fortune to meet with one at Bexhill. This Centipede does not live in the sea, but will survive prolonged immersion in salt water. It is far too valuable for us to pick to pieces, so that, if we should have the good fortune to meet with one, we should carefully examine it, making what notes are necessary, and then pickle the specimen and send it to the British Museum, Cromwell Road, S.W. The tube should be labelled with the place and date of capture, and it should be stated on the label whether the animal was taken above or below high-water mark.
The Common Millepede—often miscalled the wireworm—is readily distinguished by the absence of poison-claws, and its cylindrical worm-like appearance. De Geer, who of course adopted the Linnaean definition of ‘Insects,’ says of the Millepedes of the genus Julus, to which our Common Millepede (Ju´lus terres´tris) belongs: ‘They form, as it were, the last link of the chain which unites the class of Insects to that of Worms, for the body is elongated and cylindrical; and though they have a great number of feet, these are so short, that when these animals walk, they seem rather to glide along after the fashion of legless worms[41].’
Fig. 64.—The Common Millepede.
Dr. Sharp says that these animals do very well in confinement, and he found that sliced apples and grass formed the best food for them. He watched the process of nest-making and egg-laying, and these creatures are so abundant, and the necessary appliances so simple, that we may follow his example and see it for ourselves. His arrangements were the same as for Lithobius, and he saw the female make a hollow sphere of a bit of earth, stuck together by the secretion from the salivary glands, and smooth on the inside. A small hole was left on the top, and through this she passed in from 60 to 100 eggs, closing the aperture with earth moistened with the salivary secretion. The eggs were hatched in about twelve days. The young of all the Myriapods when they leave the egg have but three pairs of legs, but the number of limbs and segments is increased at each successive moult.
Having watched our Millepedes in confinement, it will be well to take a preserved specimen and examine it carefully with the pocket lens, so as to compare it with the Centipede; then to compare both with the common earthworm, and to note the points of likeness and of difference. The dark spots on each segment in the illustration show the stigmata.