CONTRIBUTIONS 



TO 



THE NATURAL HISTORY 



OF THK 



UNITED STATES OF AMEllICA. 



BT 



LOUIS AGASSIZ 



SECOND MONOGRAPH. 



IN FIVE PARTS.-I. ACALEPHS IN GENERAL.-II. CTENOPHORiE.-in. DISCOPHOR.E.-IV. HYDROIDiE. 

 —V. HOMOLOGIES OF THE RADIATA; WITH FORTY-SIX PLATES. 



VOL. IV. 



BOSTON: 

 LITTLE, BROWN AND COMPANY. 



LONDON: TRUBNER & CO. 



18 62. 



