IV CONTENTS. 



PAGE 



Akt. XL On Arachnactis bracliiolata, a species of floating 

 Actinia found at Naliant, Massachusetts. By A. 

 Agassiz 525 



Art. XIT. Prodromus of the history, structure, and physiology of 

 the order Lucernaria;. By Prof. IIeniiy James- 

 Clauk, of Harvard University, Cambridge, Mass. 531 



Art. XIII. Monograph of the genus Callinectes. By Albert 



OUDWAY 5G7 



Art. XIV. On tlie Fossil Crab of Gay Head. By Dr. William 



Stimi'Sox 583 



Art. XV. On Synthetic Types in Insects. By A. S. Pack- 

 ard, Jr. 590 



Art. XVI. Description of a " White Fish " or " "White Whale " 

 (Beluga borealis Lesson). By Jeffries AVymax, 

 Prof of Anatomy in Harvard College . . . 603 



Art. XVII. Remarks on some characteristics of the Insect Fauna 

 of the White Mountains, New Hampshire. By 

 Samuel H. Scudder 612 



