INTERNAL ANATOMY OF INSECTS. 187 
In the human subject only 529 have been counted*: so 
that this minute animal has 3532 muscles more than the 
Lord of the creation ! 
The muscles of the Arachnida seem less numerous 
than those of insects. In the Scorpionide they appear 
to be robust, formed of simple straight fibres, of a whitish 
gray colour: a muscular web, rather strong, clothes the 
parietes, but rarely adheres to them, of the abdomen, 
and envelopes the viscera, with the exception of the lungs, 
and probably of the heart. ‘The dorsal part of this web 
gives birth to seven pairs of filiform muscles, which tra- 
verse the liver, and are attached to a muscular riband 
which, passing above the lungs, runs the whole length of 
the ventral parietes. ‘These muscles when exposed to 
view resemble extended cords. ‘The abdominal segment 
preceding the tail is filled with a powerful muscular mass 
which moves that organ”. ‘Treviranus discovered two 
longitudinal muscles in Scorpio europeus, running from 
the breast to the tail, which above and below each gill 
were connected by another running transversely across 
the heart, thus forming a quadrangular area in which 
the gills are situate®. ‘The heart appears to be moved 
by muscles not very dissimilar to those- of the Cossus4, 
as is likewise that of the Aranezde; in Clubiona atrox 
the wider part of this organ is muscular, and incloses a 
considerable cavity®. In this tribe the muscles of the 
abdomen, the skin of which is soft and unfit to act as a 
lever to them, are attached to a cartilage, and thus their 
action is better sustained ‘. 
* [bid. 189. > N. Dict. d? Hist. Nat. xxx. 421. 
© Arachnid. 9. t.1. f. 7. 7. 4 Thrd. o. © Tbid. 19. 
® Tbid. 45. £, Wis f. 31. myn; gy 7b 
