STRUCTURE OF THE LANCELOT. 40 



internally, of a great number of layers or lamina?, each 

 of the size and shape of a section of the column at the 

 place where it is situated. When any part of the 

 column is removed, thin plates may be pushed out 

 from the tubular sheath, like a pile of coins. They 

 have no great adhesion to each other; are of the 

 consistence of parchment, and appear like flattened 

 bladders, as if formed of two tough fibrous mem- 

 branes pressed together. The fibres of the sheath 

 are chiefly circular; but there are strong ligaments 

 stretching along its superior and inferior aspects. 

 From the sides of the column aponeurotic lamina? 

 pass off to form septa of attachment between the 

 muscular bundles ; and, along the mesial plane, over 

 the column, there is a fibrous canal for the spinal 

 cord. Foramina exist along the sides of this canal 

 for the passage of nerves. The form of the spinal 

 column therefore is sufficiently marked, and about 

 sixty divisions and upwards, passing obliquely from 

 above downwards, may be counted. There are, 

 besides, a dorsal and ventral series of germs of in- 

 terspinous bones, and fin rays, between the peri- 

 pheral elements of the spinal column. 



The total want of brain, eye, and ear, in one of 

 the vertebrate animals, is scarcely less extraordinary 

 than the complete absence of any thing like a bony 

 skeleton; and yet the fact seems established on the 

 same satisfactory grounds. The nervous system, ac- 

 cordingly, consists only of a spinal marrow or cord, 

 and nerves, the latter branching from the former 

 regularly on both sides. Tfre spinal cord stretches 



