44 THE AQUAVIVAKIUM. 



of fishes (Acanthopterygii), they possess 011 their 

 backs (Fig. 5). They have also other names, as 

 Banstickle, Sharplin, Prickleback, Tittleback, &c. 



FIG. 5. 



The following are the names of the species, which 

 sufficiently characterize their forms : 



1. The Rough-tailed Stickleback (Gasterosteus 

 trachurus) (Fig. 5). This is the most common form. 



2. The Half-armed Stickleback (G. semiarmatus). 



3. The Smooth-tailed Stickleback (G. leiurus). 



4. The Short-spined Stickleback (G. brachy- 

 centrus). 



5. The Four-spined Stickleback (G. spinulosus). 



6. The Ten-spined Stickleback (G. pungitius). 



7. The Fifteen-spined Stickleback (G. spinachia). 

 It is rarely, if ever, taken in fresh water. 



There are many other sharp-finned (Acantho- 

 pterygii] fishes found in fresh water, which may 

 be kept in the Aquavivarium. 



The PERCH (Perca ftuviatilis), when it is young, 

 will live very well, and is a very handsome fish. 



The MILLER'S THUMB, RIVER BULLHEAD, or TOMMY 

 LOGGE (Cottus Gobio), inhabits most of our streams, 

 and will live a long time in confinement. It is 

 known by the peculiar flattened form of its head. 



To the soft-finned fishes (Malacopterygii) belong 

 the Roach family (Cyprinidce). To select from 

 amongst this large family of truly British fishes 

 would appear to be almost invidious. They all 

 live in fresh water. They are all, more or less, 



