Volume XVL November, J8^g. Number I. 



JOURNAL 



MORPHOLOGY. 



STUDIES ON LIMULUS. 



I. 777^ ENDOCRANIA OF LIMULUS, APUS, AND MYGALE, 



BY 



WILLIAM PATTEN and WILLIAM A. REDENBAUGH. 



Dartmouth College, Hanover, N. H. 



Introduction. 



In 1888 I began a detailed study of the anatomy and 

 development of Limtihis, for the purpose of determining 

 whether such a study would justify the conclusion that 

 Limulus and other arachnids are closely related to ancestral 

 vertebrates. That they are so related seemed probable in view 

 of certain resemblances between the mode of development of 

 the brain and eyes of Limulus and scorpion and those of 

 vertebrates. 



An elaborate attack on the problem was planned. The struc- 

 ture, development, and physiology of all the organs of Lhnulus 

 were to be worked out, and a comparison made between them 

 and the corresponding organs in vertebrates. But it was soon 

 discovered that an inquiry of this nature, made from a special 

 point of view, opens many side problems that necessitate 

 frequent digressions in order to discuss tentative homologies 



