Imperium naturæ C. Linnaeus, 1758 - nature
   Mundus Plinius - physical world
     naturalia - natural bodies
       Regnum Animale C. Linnaeus, 1758 - animal kingdom see Kingdom Animalia Linnaeus, 1758
         Class Pisces Linnaeus, 1758 see Superclass Pisces Linnaeus, 1758
           Order Thoracici Linnaeus, 1758
             Genus Cottus Linnaeus, 1758 - bullhead
               1 Cottus cataphractus Linnaeus, 1758 see Agonus cataphractus (C. Linnaeus, 1758)
               2 Cottus quadricornis Linnaeus, 1758 see Triglopsis quadricornis (C. Linnaeus, 1758)
               3 Cottus grunniens Linnaeus, 1758 see Allenbatrachus grunniens (C. Linnaeus, 1758)
               4 Cottus scaber Linnaeus, 1758 see Grammoplites scaber (C. Linnaeus, 1758)
               5 Cottus scorpius Linnaeus, 1758 see Myoxocephalus scorpius (C. Linnaeus, 1758)
               6 Cottus gobio Linnaeus, 1758 - bullhead