His most interesting observations were concerned with their mating habits, in connection with which he noted some extraordinary phenomena. After some very curious antics, in which the animals stood face to face (Fig. [167]) with raised tails, which they intertwined—evidently with no hostile intention—they always indulged in what Fabre calls a “promenade à deux,” hand in hand, so to speak, the male seizing the chelae of the female with its own, and walking backwards, while the female followed, usually without any reluctance. This promenade occupied an hour or more, during which the animals turned several times. At length, if in the neighbourhood of a suitable stone, the male would dig a hole, without for a moment entirely quitting its hold of the female, and presently both would disappear into the newly-formed retreat.

After mating, the male was often devoured by the female. Moreover, after any combat with an enemy, such as a Lycosa or a Scolopendra, it appeared to be de rigueur to eat the vanquished, and on such occasions only was any considerable amount of food consumed.

The scorpions were not, however, anxious to fight, greatly preferring to retire if possible; but when incited to combat, their sting was quickly fatal to any mature insect, to spiders and to centipedes. Curiously enough, however, insect larvae, though badly wounded, did not succumb to the poison. Newly-hatched scorpions mounted on the mother’s back, where they remained motionless for a week, entirely unfed. They then underwent a moult, after which they were able to forage for themselves.

External Structure.

The chitinous plates of the prosoma are fused to form a carapace. Six segments are clearly indicated by the six pairs of appendages, but, though the development of Scorpio affords little direct evidence of the fact, there is reason to believe that there once existed a pre-cheliceral segment,[[241]] as has been clearly proved in the case of the spiders. An embryonic pregenital segment has also been recognised. The six prosomatic appendages are those proper to the Arachnida, being the chelicerae, pedipalpi, and four pairs of ambulatory legs. The mesosoma, which is broadly attached to the prosoma, comprises six segments, indicated ventrally by the genital operculum, the pectines, and the four pairs of pulmonary stigmata. The last of the broad abdominal segments, which tapers abruptly, belongs to the metasoma, which also comprises six segments, and is succeeded by the post-anal spine or sting.

Prosoma.—Near the middle of the carapace are two median eyes, and on its antero-lateral borders are usually to be found groups of smaller eyes, numbering from two to five. All the eyes are simple. There is a difference, however, in their development, the median eyes being diplostichous, or involving two layers of hypoderm, while the lateral eyes are monostichous, and pass through a stage strikingly like the permanent condition of the eyes of Limulus. The arrangement of various slight longitudinal ridges on the dorsal surface of the carapace is of systematic importance. On the ventral surface, just in front of the genital operculum, is a sternum, never large, and sometimes barely visible. Its shape and size constitute one of the principal family characteristics.

Fig. [169].—Buthus occitanus. A, Dorsal view; B, ventral view. (After Kraepelin.)

Mesosoma.—The dorsal plates or terga are distinct, and are connected by soft chitin with their corresponding sterna.

Beneath the second abdominal segments are borne the “pectines” or comb-like organs. In their structure four portions are distinguishable, an anterior lamella or shaft attaching them to the body, a middle lamella, the teeth, and the fulcra, a series of small chitinous pieces intercalated between the bases of the movable teeth.