NOTES TO THE 



ninety-one vertebrae. Professor Owen writes : " The vertebrae 

 are ' Procaelian ' that is, they are articulated together by ball- 

 and-socket joints, the socket being on the fore part of the 

 centrum, where it forms a deep cup, with its rim sharply 

 defined, the cavity looking not directly forwards, but a little 

 downwards from the greater prominence of the upper border." 

 In my museum I have the tanned skin of a boa-constrictor, 

 fifteen feet long ; it would have been interesting to have 

 known how many vertebrae this snake worked. The reader can 

 easily examine the structure of snakes' vertebrae for himself; 

 take a snake, the bigger the better (one that has been in spirits 

 will do quite well) ; cut off his head ; run a wire down the 

 spinal column as far as it will go ; tie the two ends of the wire 

 together, and boil the snake till the flesh can be easily removed 

 with a knife and brush ; the vertebrae will then be found to be 

 strung like the beads of a lady's necklace. 



NEST OF STICKLEBACK, p. 58. Birds, as we know, build 

 nests, but at first sight it would seem extraordinary that a 

 fish should also build a nest, yet it is so. The sticklebacks 



NEST OF SEA STICKLEBACK. 



are the nest-builders. There are three well-marked species 

 fif sticklebacks in England ; two inhabit fresh water, namely, 

 Gasterosteus aeuleatus, which has three spines, and the Cf. 

 pungitius, which has ten spines ; the third kind, G. spinachia, 

 lives in the sea, and has fifteen spines. The fresh-water 

 stickleback's nest can be found in the month of May; my 

 readers should look out for them. In October, 1866, I received 



