3° 



DESIGN IN NATURE 



PLATE XV 



,iirri!/(^'fiTiiy' 



Fig. 2. 



Plate XV. illustrates spiral formations in shells and horns. 



Fio. 1. — Shows typical pyramidal-shaped, right-handed shells which hear a marked resemblance to many horns. 



A. tiodellaria curvirostrix. D. Fasciolaria tulipa. 



B. Tcrebra dimidiata. E. Fusm dapetit-thouardi. 



C. Turritdla (s]i.). 



Uracil 1iy C. Beijeau from photographs by the Author. 



Fiu. 2. — Shows typical right and left-handed spiral horns. These horns, especially those figured at F, bear a striking resemblance 

 to the spiral shells (Fig. 1 of this Plate). 



A. Head and spiral horns of West African harnessed antelope {Tragdaphus gratus). 



B. Head and spii'al horns of the Addax antelope {Adda.i- nasomaciilatus). 



C. Head and spiral horns of Grant's gazelle {Ga::eUa ijranti). 



]}. Head and spiral horns of the black buck {Aiitilope cervicapra). 



E. Head and spiral horns of the Angora goat {Capra liircm). 



F. Head and spii'al horns of the Markhor goat {Gapra falconen). 

 Drawn by 0. Berjeau for the Author. 



PLATE XVI 

 Plate xvi. illustrates spiral structures as seen in shells, horns, tusks, teeth, feathers, proboscides, tentacles &c. 



Fig. 1. — Skull and s]>iral horns of the Panur sheep {Ovin poli) (after Sir V. Brooke). Shows beautiful right and left-handed 

 spirals. 



Fig. 2. — A. Head and spiral tusks of mammoth {ElepUas primigenms) (after Tilsius). The great tusks of the mammoth furnish 

 striking examples of spiral formations in the animal kingdom. 



B. Head, tusks, and spiral trunk of the African elephant [Elephas africanus). The trunk of tlie elepjhant supiilies an example of 

 a soft, yielding, temporary spiral, similar to that seen in the tail of the spider monkey, the two-toed ant-eater, Merian's opossuni and 



