230 ANIMAL SKETCHES. CHAP. 



Thornie is as well provided with defensive armour as it is 

 with offensive spears. A female which lies before me is 

 2f inches long and | of an inch in maximum depth, with 

 ventral spines J of an inch in length. But specimens have 

 been found 3J inches in length. The males are some- 

 what smaller. 



The Thornie's first cousin, the ten-spine or Tinker, 

 differs from him considerably in external appearance. The 

 male in full colour is a deep velvety black. It is also a 

 smaller fish, a narrower and more slender. I have no spirit- 

 specimens at hand, and I do not care to put one of my 

 little friends to the inconvenience of being half-drowned 

 (in air) for the purpose of scientific measurement. I should 

 say the average length is from 1 J to If inches, the depth 

 being J of an inch. They too are armed with ventral 

 spines, while on the back there are ten, or more frequently 

 nine, closely-set spines. On minute inspection they may 

 be seen to be set in two rows, neither of which is quite in 

 the mid-line of the back. There are thus five on one side, 

 and four on the other. The appearance is as if the first, 

 third, fifth, seventh and ninth, had been pulled over just a 

 little to one side, while the intermediate spines had been 

 pulled over just a little to the other side. 



The nest -building habits of this species differ consider- 

 ably from those of his three-spined cousin. For whereas 

 the three-spined invariably (I believe) builds on the ground, 

 the ten-spined as invariably (I believe) builds in the water- 

 weeds. He despises the adventitious aid of horse-hair, 

 and seems to prefer the fine threads of green alga?. The 

 nests my little friends have built have usually been about 

 as big round as the girth of a florin, and have a not quite 

 horizontal passage through them. The courting male is not 

 so rude as to dig his mate in the ribs with his nose ; such 

 a mode of courtship would ill accord with his aristocratic 



