INSECTA. 

 Fig. 400. 



937 



D'uitjram of the rnmelei and nerrei of the renlral mrface of tlte teymenti in the lama 

 ,if S/ihinjr ligtuiri. (Newport, Phil. Trata.) 



beneath iho upper one. The second layer con- 

 sists nl" seven distinct fasciculi, wliich extend 

 from tin 1 anterior margin of the segment, close 

 to the smaller rectus, and beneath the larger, 

 about half their breadth across the segment. 

 They run backwards and outwards in a dia- 

 gonal direction, and are attached to the middle 

 ridge below the rectus as for across the seg- 

 ment as the outer margin of that muscle (8). 

 layers of muscles when in action draw 

 the outer part of tln< anterior margin of the 

 following segment diagonally forwards in the 

 direction of the median line of the body, 

 and, consequently, win i uscles in se- 



veral segments on one side of the body act 

 ogether, they brinj; forward the posterior |>or- 

 iou of the body of the same side, and bend 



it in a semicircular direction. When these 

 layers on both sides of a segment act together, 

 they draw forwards the posterior part of the 

 body in a straight line. The most internal 

 of these layers (6) which lies close to the rectus 

 may be called the first oblii/ue, and the other 

 the second ublii/ue (7). Beneath this there is 

 another diagonal layer of fibre* which originates 

 close to the median line of the body (9), be- 

 neath the nervous cord, almost in a line with 

 the insertion of the smaller rectus. The origin 

 of tins set is exceedingly narrow and distinctly 

 tendinous, and the fibres diverging |>ass di- 

 K upwards and outwards, forming a flat 

 triangular muscle, the third oblique (9, 10), 

 is attached to the posterior ridge, and 

 extends outwards to the margin of the greater 



