XII HABITS—-EXTERNAL STRUCTURE 301 
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,’ 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, in- 
dicated ventrally by the genital operculum, the pectines, and the 
four pairs of pulmonary stigmata. The last of the broad ab- 
dominal 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 
1 Brauer, Zeitschr. wiss. Zool. lix., 1895, p. 355. 
