APPENDIX. 221 



Fig. 5. — Left cf 5 is the small or superior Y shaped bone. 

 Right of 5 is the larger or inferior Y shaped bone. 



Fig. C. — Left of G is the short bone (one of a pair) page 164. 

 Right of 6 is the bone e, plate 10, page 175. — [Figs. 5 and 6 are 

 from same fish as plate 11.] 



In order to make plate 11 more clear, I have to add. 



The spinal chord (myelon) passes upon the dorsal aspect of the 

 centra, covered by a very strong sheath, which lies between the 

 ventral extremities of the dorsal spinous rays until it reaches the 

 end of the vertebrae, it there divides into two principal filaments 

 which are inclosed in a wire at the anterior extremity of the 

 upper or small Y shaped bone. One of these filaments lies upon 

 the notochord, following it to its extremity, where it becomes 

 minutely divided and lost in the general structure. The second 

 or posterior dorsal wire, incloses the notochordal branch ; the other 

 I have not attempted to follow. 



The notochord passes from the posterior edge of the spongy 

 centrum (page 170) between the forks of two Y shaped bones, 

 lying upon the upper edge of the superior and shorter one, and 

 extends following the curve of the dorsal long fin ray at its 

 superior edge, being overlapped by the longest of the short fin 

 rays (in this specimen 2 inches in length) next to the long fin ray 

 a distance of ll$ inches. The centre of the notochord being 

 exactly half an inch from the dorsal edge of the caudal fin, where 

 in plate 11 it is marked by a wire. The notochord where it 

 issues from the forks of the superior Y shaped bone, in this 

 specimen is nearly % of an inch in diameter, decreasing a little in 

 size until near its extremity, where it is slightly enlarged and 

 has a somewhat blunt rounded termination ; it is jointed in 

 structure or rather shows the divisions which in the body of 

 the fish form the centra. 



The wire loop nearly in a line with the centre of the spinal 

 column, plate 11, includes the nervous corpuscle (page 170,) which 

 receives filaments from a ganglion by a branch from the spinal 

 chord. 



On the left side of the tail, plate 10, figure 4, are shown the 

 orifices of the pulsating ? sack (page 170) ; the other part of the 



