1888.] NATURAL SCIENCES OF PHILADELPHIA. 105 



Naevus bearing abundant growths of hair has been found by J, 

 Nevins Hyde ^ confined to the left side of the body in tlie form of 

 three bands which followed in the direction of the intercostal nerves; 

 a fourth band extended from the perineum to the scrotum and 

 penis. 



6. Antero-posterior Asymmetry. — The anterior half of the 

 body may be disposed with reference to the color marks and the 

 quantity or kind of hair, in a manner different from the posterior. 

 This disposition is strikingly seen in many specimens of the tapir, 

 the anterior part (with the exception of the lips which are white), 

 being dark, while the posterior is white. In Hystrix the posterior 

 half of the body alone bears the quills. In Phascolardos the poster- 

 ior half of the body is white. In Hapale hicolor a similar coloration 

 is seen. In Chrysochloris aurata the posterior half only of the body 

 justifies the name. 



Concluding Remarks. — In reviewing the subject of the distribution 

 of color marks in mammals it is evident that the causes of the ar- 

 rangements are various, and do not admit of easy solution. The 

 points which I have attempted to elucidate do not invalidate biolog- 

 ical principles already established, while it must be acknowledged 

 that some of them do not remain explained by these principles alone. 

 That variations of deep lying structures will influence the periphery 

 which over-lie them is a well established law. Illustrations are seen 

 in the relations which exist between the true organs of generation 

 and the skin coverings over them. It is but another application of 

 the principle to find the sacral spot correlating to conditions of the 

 neuro-enteric canal, and yet another in the skin about the nostril, 

 the eye and the auricle remaining black because the true organs of 

 olfaction, vision and audition also contain black pigment. The 

 principle of antero-posterior symmetry — of bilateral symmetry and 

 asymmetry are also illustrated. 



The general contrasts of the color marks of the head as opposed 

 to those of the body, which are so common in parti-colored animals, 

 may be explained by the enormous influence which the brain must 

 exert over the nutrition of the entire region. That nerve-endings 

 can influence the color of the integument near them is abundantly 

 proven. From the lateral line of teleostean fishes to the ground 

 hackie is a long series in which the influence of nerve endings on 

 the sides of the trunk can be associated with color marks. Sebaceous. 



1 Chicago Med. Journ. and Examiner, Oct. 1877. 



