xlii. t>fcfcSIDBNT*S ADDRESS. 



of articles on "Mammalia" in the eighth edition of the 

 " Encyclopaedia Britannica." The remarkable series of illustra- 

 tions of variation, coloration, mimicry, and the anatomy of 

 vertebrates which adorn the cases of the Central Hall of the 

 Museum are in themselves a monument of his genius. 



I now turn to the subject of my Anniversary Address, which is 

 a continuation of that of last year, dealing with higher organisms 

 than that of the mollusca, on which it treated. 



There is no section of the animal kingdom which in its 

 embryonic metamorphoses exhibits so many types and parallels 

 by which their ancestry can be traced as that of the vertebrates. 

 The changes are of peculiar interest to the biologist, in 

 comparing the fossil types through which the embryo passes to 

 maturity. With the exception of the lowest forms of fish, all 

 vertebrates have a dorsal column and a cartilaginous skeleton in 

 the embryo state ; a few only continue in this stage, the greater 

 part of them assimilate lime, and other mineral substances for 

 ossification. 



Fish, which are the lowest type of vertebrates, have special 

 modifications which enable them to live in the water, move 

 through it with rapidity, and utilize it as a medium for respira- 

 tion. 



The skeleton consists primarily of a vertebral column, 

 more or less perfect, which, at the anterior extremity expands 

 into a skull, which protects the cephalic portion of the 

 neural-axis to which the organs of sense are connected. 

 The canal for the lodgement of the neural-axis lies on 

 the upper side of the column. In addition to the head, trunk, 

 and tail, the skeleton has, in ordinary cases, a set of bones which 

 give support to two pairs of limbs ; those belonging to each pair 

 are connected with the vertebral column, by a peculiar arch of 

 which the anterior is termed the " scapular," the posterior the 

 " pelvic." In many vertebrates, although the internal skeleton is 

 fully developed, there is an external or dermal-skeleton as well. 

 '1 In- dermal-skeleton is sometimes composed of true bone. This 

 is the case in the Lepidosicus and Ostracion among existing 



