OR, THE HOME-CULTURE OF FRESH- WATER PLANTS. 



its victim. They are also pursued and devoured by 

 the voracious Water Beetle (Dyticus marginalis), 

 whose horny forceps defy the armour and spinal 

 defences of this formidable little fish. 



Block states that the duration of the life of the 

 Stickleback is three years ; and the observations of 

 other naturalists appear to confirm this opinion. 



Mr. Yarrell divides the genus Gasterosteus into 

 several species, all of which are tolerably well 

 marked. The first is termed G. trachurm, or 

 Rough-tailed Stickleback; his defensive plates of ar- 

 mour continuing all along the side to the tail, upon 

 which they appear to terminate in minute spines. 

 The second is called G. semiarmatus, or half-armed, 

 his defences not continuing above three plates be- 

 yond the pectoral fin. The third, G. leiurus, or 

 Small-tailed Stickleback, the side plates being less 

 conspicuous and not extending beyond the pectoral 

 fin. The fourth, G. brachycentrus, or short-spined 

 kind, as large as the first or second species named, 

 but having the spines on the back much shorter. 

 The fifth has been termed G. spinulosus, the four- 

 spined species, much smaller than the last named. 

 Probably from feeling himself more completely 

 armed, however, he is more decidedly pugnacious 

 than his larger relatives, even in confinement. The 



