362 
NOTES TO THE 
ninety-one vertebrae. Professor Owen writes : — " The vertebrae 
are ' Proccelian' — 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 cujd, 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 vertebrcB this snake worked. The reader can 
easily examine the structure of snakes' vertebrse 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 vertebrse will then be found to be 
strung like the beads of a lady's necklace. 
ISTest 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 
of sticklebacks in England ; two inhabit fresh water, namely, 
Gasterosteus aculeatus, which has three spines, and the G. 
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 
