151 



nerves) do not always escape from the vertebral canal opposite to 

 the points from which they rise; in Lophius, for example, they 

 escape much lower down ; and the kind of sheath which they 

 form for the marrow has caused the error of those anatomists 

 who say, that this species is deficient in a spinal marrow." 

 {Cours d'Anat. Comp. 3d edit, T. iii. p. 176.) 



In the present dissection, the most striking peculiarity, on 

 opening the spinal canal, was the existence of an immense num- 

 ber of bundles of nervous fibres, which so completely filled it 

 that the spinal cord was wholly concealed ; this was only ex- 

 posed after the whole mass had been removed, aud the bundles 

 of nerves, united together by loose cellular tissue, carefully 

 separated from each other ; they formed, as Cuvier expresses it, 

 a "sheath" around the spinal marrow. This last was traced as 

 far as its termination, which was quite near to the tail, when it 

 enlarged, as shown in the specimen, into a very distinct terminal 

 ganglion. The cord below its anterior third is very much con- 

 tracted in size, and presents a very remarkable contrast to the 

 vastly greater bulk of nerve bundles by which it is surrounded. 

 This disproportion does not seem to have attracted attention. It 

 is not uncommon for a nerve to be increased as to its apparent 

 size after leaving the spinal canal, in consequence of the addi- 

 tion of a thick sheath, so that the apparent bulk of a bundle of 

 nerves, as of the trigeminus, is after its escape from the crania] 

 cavity greater than before, and at the same time seems large in 

 comparison with the vertebrae from which it is given off. In 

 this case, however, the nerve bundles which are still in the spinal 

 canal acquire great bulk and are out of the ordinary proportion 

 to the cord itself. The opposite state of things exists in Siren 

 lacertina among reptiles, where the bulk of nerve bundles in the 

 canal is very much less than that of the cord, and the same is 

 true of most fishes. Thus in the one case we have the sum of 

 the nerves more voluminous than the cord which supplies them, 

 while in the other extreme the volume of the cord is much larger 

 than that of the nerves. 



Dr. C. T. Jackson exhibited a daguerreotype of a fossil 

 fish from Hillsboro', N. B. He suggested that the daguerre- 

 otype process would afford an excellent method of pre- 



