2<> PHYSIOLOGICAL SERIES. 



earth, and show the proportion of animal substance, which 

 in this species is very considerable. 0. C. 112. Hunterian. 



A. 62. Bone of the pectoral fin of a Cod-fish (Gadnn morrhua), 

 similarly treated. 0. C. 115. Hunterian. 



A. 63. Some bones of a fish (Udone?) from the South Seas, 

 showing a green colour. 0. C. 219 C. JIunterian. 



A. 63 a. Various bones of a Gar-fish (Belong mdgaris). The 

 matrix of the bone is of a green colour due to Vivianite 

 (ferrous phosphate). 



A. 63 b. Diagrams showing the proportion of the constituents 

 of a Haddock's bone (Gadns ceglefinus). It will be seen 

 that nearly 50 % of fresh bone is water, that calc. phosphate 

 is nearly the sole inorganic constituent, and that about 

 18*5 % is organic. The analysis was made by A. Gordon 

 Salamon, Esq. 



Structure. 



A. 64. Cartilaginous skeleton of a freshwater Lamprey (Petro- 

 myzon flumatilis). The axial rod (notochord), that extends 

 nearly the whole length of the animal, consists of large 

 vacuolated cells polygonal by mutual pressure, the matrix 

 forming an extremely thin separating layer between the 

 cells. In the other cartilages the cells are also polygonal 

 from pressure, but the matrix is more abundant^ forming a 

 definite layer around each cell ; the combined thickness of 

 the matrix between two cells being about a fourth of the 

 diameter of a cell. 



A. 65. Transverse and longitudinal sections of the body of a 

 Sea-Lamprey (Petromyzon marimts), showing the relations 

 of the notochord. It is surrounded by a double sheath 

 composed of an inner fibrous layer that can be split into 

 three sheets according to the course of the fibres, and a 

 thin homogeneous outer layer (elastica externa). The 

 sheath is itself enveloped by a considerable quantity of 

 dense skeletogenous tissue. 



v, Ebner, Zeitschr. wiss. Zool., Bd. Ixii. 1896, p."469. 



