14 iOWA ACADKMV OF SC Il.NCKS. 



the moutli of the Niobrara, indicates th:il the drift ui'iit ioiic I 

 H'as deposited under water. 



<S. The rehitioii of the till to certtiiii deposits of Noh-aiiie 

 ashesi whieh in some eases are helow the drift, and in other 

 loealities are in it antl ahove the till, suizii-ests a possihl.' 

 demonstration of the suh-aqiieoiis origin of th" till undei- con- 

 sideration. This asli deposit was made in still water. If 

 there was ))ut one deposition of volcanic aslics ^ancl there is 

 no proof yet known that such was not t!ie fact), the evidence 

 would 1)e complete. 



DIRECTIVE COLORATION IN ANIMALS. 



The pa|)er was the outu'rowth of ohscrxations made on the 

 Western plains. It is puhlished in full in the Aiii(n-k-(iu 

 JVaiurah'sf for ISSS. 



While recoiiui/ini^- the validity of protecti\e, ornamental 

 and typical coloration, as defined hy Dai'win, \\'allace. Belt 

 and others, the writer claimed that a very considerable 

 amount of coloration in animals remained unexplained. For 

 such as are of service somewhat after the manner of dis- 

 tinctive bada-es and uniforms to troops, or as signal Haas and 

 lio^hts to l)oats and cars, he jiroposed the name directive 

 coloration. 



The following synopsis presents the ])rincii>al features aiul 

 applications of the principle. 



Directive (M:)loration is tliat which is in any way useful to a 

 species by assisting in nuitual recognition between individ- 

 uals, or by indicating one to another their attitude and i)r()b- 

 able movements. To this head are referr(!d : 



1. Marks and tints promoting recognition at a dis- 

 tance, to guide in straggling flights, or to bring stragglers 

 together, [A]. 



2. Those indicating the attitude of body, and its prob- 

 able movement. [P>] in darkness; [('] in close movements of 



