24 INTRODUCTION 



coast extend from Cape Cod northward; the American, from 

 Cape Cod to Cape Hatteras ; the West Iiidian, from Cape Hattc- 

 ras southward. On the Pacific coast the divisions, without defi- 

 nite names, are from the Isthmus to Acapulco, Acapulco to the 

 Gulf of California, Cape Lucas to the Strait of Fuca. These 

 divisions merge at indefinite lines, but the above limits are 

 generally accepted as the points of broad division. 



The shore or littoral fauna is especially abundant and com- 

 prises more species that are curious in form and beautiful in 

 color than the others. The invertebrates of the deep sea are 

 mostly transparent and of a blue or violet tint, while the fishes 

 are gray or bluish above and white beneath, which renders them 

 inconspicuous to their enemies. 



