I02 PATTEN AND REDENBAUGH. [Vol. XVI. 



I. Historical. 



Before the year 1872 we find little mention of the nervous 

 system of Limulus, although a number of papers had appeared 

 upon the natural history, histology, and systematic position of 

 the King Crab. Van der Hoeven, in 1838, published a mono- 

 graph upon the anatomy of Limulus, in which he gave a very 

 good account of the external form, appendages, and grosser 

 internal anatomy. In the same year Milne-Edwards made 

 the first observations upon the development. Gegenbaur, in 

 '58, described the histology of some of the tissues of Limulus. 

 Lockwood, in '70, Dohrn, in '71, and Packard in '72, con- 

 tributed considerable to our knowledge of the embryology of 

 the animal. 



The first important description of the nervous system ap- 

 peared in a paper by Owen in '72. He figured the brain and 

 ventral cord, and the principal nerves arising therefrom. 



Milne-Edwards, in '73, carried the investigation of the 

 nervous system much further, and also gave a very complete 

 account of the circulatory system. 



In '80 Packard described the histology of the digestive sys- 

 tem, structure of the liver, nephridia and eyes, and gave 

 some observations upon the brain, particularly its internal 

 structure and development. In '93 he published further 

 observations upon the brain with notes upon its embry- 

 ology. In this paper he deals almost entirely with the 

 internal structure. 



Lankester, in '84, described the skeleto-trophic tissues and 

 coxal glands, and in '85, with the assistance of W. B. S. Benham, 

 the muscular and endoskeletal systems. 



In '89 Patten gave a short account of the development of 

 the brain, and in '93, treated of it in greater detail, tracing the 

 later modifications to practically the adult stage. 



In the year '93 Viallanes, also, published a paper upon the 

 brain of Limulus ; and Miss Ida H. Hyde investigated the 

 nervous mechanism of the respiratory movements of Limulus, 

 and maintained that the respiratory centers were located in the 

 ventral cord. 



