370 MOSTLY MAMMALS 
shield-like carapace, upon the upper surface of which are 
carried a variable number of simple eyes, one pair of which 
is larger than the others, and is placed dorsally, while the 
smaller ones are marginal. The first pair of appendages are 
modified into short nipping claws, while the jaw-appendages, 
technically known as maxillary palpi, are greatly enlarged 
to form the huge pair of pincers carried on each side of the 
head ; and the four pairs of walking legs are supported by 
the first four segments of the thorax. It is important to 
add that by means of lung-sacs opening by four pairs of 
apertures on the sides of the abdomen, scorpions breathe 
air, and it is accordingly only in rocks of fresh-water 
origin, or such as were deposited near the shore, that their 
remains are likely to be preserved. 
According to the most recent classification, existing 
scorpions are divided into four families, of which the first 
two are again divided into several sub-families. An im- 
portant feature in this classification are the so-called “ pedal’ 
spurs,” which are found upon the articular membrane con- 
necting the foot, or terminal segment of the legs, with the 
segment that precedes it. The Scorpionzdae, or typical 
scorpions, have only one such spur, whereas two are present 
in the other three families. It will be unnecessary to further 
consider the classification of the group in this place; but 
it is important to notice that one of the sub-families of 
the Scorpionzdae is confined to Africa south of the Sahara, 
and the Indian and Malayan countries ; while another has 
representatives not only in those regions, but also in 
northern South America and Australia. At the present 
day, indeed, scorpions are found in Europe only in the 
more southern countries, where the majority of the species 
are of comparatively small size; and it is in the tropical 
and sub-tropical regions of the globe that the group attains 
