ANATOMY AND GENERIC CHARACTERS OF SCORPIONS. 577 
The genera adopted by Peters appear to me to be, in most cases, unnecessary, often 
not even justifiable as subgenera. He has at the same time rendered great service by 
pointing out the confusions which have arisen in the use of the generic terms of one 
author by another, in new and unjustifiable senses. 
Thorell has added a number of genera to the already superfluous list, and has 
modified Peters’s classification in what appears to me to be a retrograde spirit. He 
recognizes four families of Scorpions, viz.:—(1) the Androctonide, corresponding to 
Peters’s Androctonini and Centrurini combined; (2) the Telegonidee, identical with 
Peters’s Telegonini; (3) the Vejovide; and (4) the Pandinoidie, the last two resulting 
from the breaking up of Peters’s Scorpionini on no assigned grounds. 
Both Peters and Thorell make use of the presence or absence of a keel on the 6th 
metasomatic segment as a means of generic distinction, and of other characters even 
more trivial. The small value of such characters is shown by the fact that the common 
American Scorpion, the Scorpio americanus of De Geer, is sometimes provided with a 
spine below the sting, and sometimes has none. 
In order to appreciate more clearly Peters’s four groups of Scorpions, we may refer 
to four types which are figured in the Plates accompanying this memoir, viz. for the 
TrLecontnt the Telegonus of Tasmania, Pl. LXXXII. figs. 5, 8, and Pl. LXXXIII. 
figs. 5, 6; for the Scorpronini the Scorpio cyaneus and S. Kochi of Ceylon, Pl. LX XXII. 
figs. 1, 10, 19, and Pl. LX XXIII. figs. 9,10; for the Cenrrurini the Androctonus 
americanus, Pl. LXXXII. figs. 6, 13, 17, and Pl. LXXXIII. figs. 3, 4; for the 
AwproctTonini the Androctonus funestus of North Africa, Pl. LX XXII. figs. 2, 14, 15, 
and Pl. LX XXIII. figs. 1, 2. 
My observations, which relate not only to the characters made use of by Peters, but 
also to two points of internal structure, viz. (a) the disposition of the segmental ganglia 
and their great nerves and (6) the sculpturing of the lamellz of the lung-books, have 
led me to the conclusion that the existing species of Scorpions should be gronped in 
two and not in four primary divisions; the first group, or Scorpionini, corresponding to 
Peters’s Telegonini and Scorpionini combined, whilst the second group, the Androcto- 
nini, correspond to his Centrurini and Androctonini combined. 
It appears that the linear compressed sternum of the Telegonini may be regarded as 
only an extreme form of the broad pentagonal sternum of the Scorpionini. In both 
series there is but a single row of teeth in each ramus of the chelicera, except a single 
tooth of a second row on the movable ramus in some species of Telegonus (Pl. LX XXIII. 
fiz. 7). But what is of far more importance is that in both Telegonini and Scorpionini 
the ganglia of the nerve-cord and their off-springing nerves are arranged as shown in 
the woodcut, fig. 2, B, whereas in the Scorpions of Peters’s groups Centrurini and 
Androctonini these structures have the arrangement shown in drawing, fig. 2, A, C, D 
(p. 378). ‘This difference may be described by saying that in the Scorpionini (incl. 
Telegonini) only the region of the first pair of lung-books is innervated from the 
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