The Nervous System of Chelifer 



WILLIAM A. HILTON 



There has been very little published on the nervous system and 

 sense organs of arachnids and almost nothing on pseudoscor- 

 pions. There are, however, a large number of iDapers dealing 

 with the classification of the latter and a few anatomical papers, 

 such as those of Bertkau '87, Croneberg '88 and Supino '99. I 

 have not seen these three works. There are no references given 

 to them by the recent investigators of the arachnid nervous 

 system. 



Some of the early work dealing with the central nervous 

 system of Arachnida we find recorded in the papers of Tre- 

 viranus '16 and '32, Brandt '40, Grube '42. These authors 

 describe and figure in a general way the external form of the 

 nervous system of spiders. A more recent paper is that of 

 Schinikewitch '84. This author considered the brain of Epeira 

 and determined two regions in the supraesophageal ganglion, an 

 optic region connected with the optic nerves, and a mandibular 

 connected with nerves to the mandibles. Saint Eemy '90 has an 

 extensive contribution to the nervous system of spiders. He 

 considers especially the brain in which be names the two chief 

 regions, the ocular and the rostro-mandibular because the so- 

 called mandibular nerve supplies the upper parts of the head as 

 well as the chelicerae. Many details of structure are given for 

 the genera, Lycosa, Thomisus, Epeira, Tegenaria, Drassus, 

 Segestria, PJiolcus and Eresus. Something to correspond to 

 mushroom bodies of insects is recognized in the posterior strat- 

 ified body located in the uppermost part of the head in a lobe at 

 the posterior dorsal region of the brain. 



The paper of Lambert '09 is chiefly an embryological study 

 of parts of the nervous system of Epeira. He figures the adult 

 brain of Argiope with cheliceral and mandibular branches 

 coming off from the subesophageal ganglion, or at least farther 

 from the optic mass than they are usually described and figured. 

 More recent papers on the nervous system of spiders are those 



