( 308 ) 



years ago I mj'self^) collected some data, by means of which 

 I endeavoured to justify the hypothesis, that in two species of sharks 

 {Scyllium Catulus and Sc. Caniculd) the deep-coloured transversal 

 stripes correspond alternately with groups of fn^e and of three 

 segments, producing more pigment than the other segments. 



My present endeavour will be to demonstrate some systematical 

 views concerning the colourmarks on the skin of the vertebrates 

 (birds excepted), on the basis of the rather extensive and detailed 

 knowledge Ave possess about the segmental innervation of the skin. 



To that purpose the first thing to be done is to define as clearly 

 as possible the object of my investigations. In every animal the 

 so-called "design" in its widest acceptation, originates in the con- 

 trasting effect of at least two colours or tints. Generally the next 

 proceeding is to select one of these colours, that is then regarded 

 as the "design" in a narrower sense, whilst the other colour is 

 called the prime-colour. This choice is principally determined by 

 esthetic motives : its criterion being either the difference in extension, — 

 the less extensive colour being then taken for the design — , or 

 else the difference in tint, the lightest tint being then regarded as 

 the prime-colour. The irrationality of this method is evident, as has 

 already been pointed out partiall}^ hj J. Zenneck ^) a disciple of 

 EiMER. For when comparing together a few cartoons of eqnal size, 

 on which are designed respectively: a small black figure with a 

 large white margin, a small white figure with a large black margin, 

 a lai'ge black figure with a narrow white margin and a large white 

 figure with a narrow^ black margin, — nobody will think in 

 either of these cases of taking the margin for the design : the figure 

 remains the figure, whether it be large or small, black or white. 

 Consequently it is neither by its tint, nor by its extension that the 

 "design" ought to be distinguished, but only and exclusively by its 

 significance. Applying this test to the distribution of colourmarks 

 on the skin of animals (the design in its widest acceptation) we will 

 accordingly have to determine at the outset in each case, which 

 biological, morphological and physiological significance must be 

 ascribed to the different portions of the design. 



Their biological significance m^xj be neglected here; necessarily the 



1) G. VAN RiJNBERK, Beobachtungcii über die Pigmentation der Haul von Scyllium 

 Catulus und Ganicula und ihre Zuordnung zu der segmonlalen Hautinnervation 

 dieser Thiere. — Petrus Camper, Vol. Ill, 1904, pari. 1, p. 137—173. 



2) J, Zenneck, Die Zeichnung der Boiden. Zeitschrifl f. Wisseuschaftliche Zoölogie, 

 Bd. 64, 1896, h. 1, u. 2, S. 234. 



