CHAPTER’ V 
THE MILLER’S THUMB AND STICKLEBACKS 
The Millers Thumb—Distribution—Habits—The Three-spined  Stickle- 
back — Appearance — Habits — Distribution — The Ten-Spined Stickle- 
back. 
Eighth Sub-Order: ACANTHOPTERYGII COTTO-SCOMEBRIFORMES: THE 
BULLHEAD AND MACKEREL-LIKE SPINY-FINNED FISHES. 
Havine disposed of the three members of the Perch 
Family inhabiting the fresh waters of Great Britain, we have 
to descend a long way in the classified scale before reaching 
the next fish found in our streams and lakes. This brings 
us to the eighth sub-order of Acanthoprerygii, distinguished by 
Dr. Giinther as Cotto-scombriformes, the bullhead and mackerel- 
like sub-order, which is arranged in fifteen families, embracing 
fish of most diverse, and often of very grotesque, aspect. The 
john dory, the tunny, the weever, the angler or fishing- 
frog, and the gurnards are among the best known members 
of these families, and differ from each so widely in habits and other 
appearance that it may puzzle the student at first to understand 
how they can be classed together under any “ natural”’ system. 
It must be confessed that, just as the whole order of spiny- 
finned fishes do not form a perfectly consistent group, so 
this sub-order presents some puzzling anomalies. One fin at 
least is always spinous; but the spinous dorsal fin is not 
always present, and in some families the spines have become 
modified into tentacles, as in the hideous fishing-frog or 
sea-devil (Lophius), and even into suctorial discs, as in the 
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