230 Journal of Comparative Neurology. 



the complex eyes as secretions from the retinal cells, which 

 view does not seem probable. 



Finally, it may be added that Charybdea is very sensitive 

 to light, as is fully shown by Conant's physiological experiments, 

 but none of these trace the seat of sensation directly to the so- 

 called eyes of the sensory clubs, so that the evidence that these 

 are real eyes is almost wholly histological. 



Johns Hopkins University, August 23d, 1898. 



A Contribution to the Nervous System of the Earth- 

 worm. 



By H. R. Fling. 



The past three years, under the direction of Dr. C. O. 

 Whitman, at Chicago University, and at the Marine Biological 

 Laboratory at Wood's Hole, Mass., I have been carrying on 

 investigations to determine the typical segment of the Earth- 

 worm and to homologize as far as possible the head segments 

 with the typical segment. I take this opportunity of present- 

 ing some of the reconstructions which I have made, reserving 

 until a later time the details and discussion of homologies. 



In 1894 Dr. Richard Hesse published an article entitled 

 " Zur Vergleichenden Anatomic der Oligochaeten, " in the 

 ^^ Zeitschrift fiiv wissenschaftlicJie Zoologic" 3 Heft, Band 58. 

 Besides giving a description of the nerves in a typical segment, 

 he reconstructed the nervous system of the head segments. 

 The following year Miss Langdon published an article " Lum- 

 bricus Agricola Hoffm," in Journal of Morphology, XI, pp. 



193-234. 



In both of these papers the arrangement of the nerves in 

 the typical segment was described as consisting of a ventral cord 

 with a ganglionic enlargement at the posterior part, from which 

 two nerves take their origin, and a third nerve leaving the an- 

 terior smaller part of the cord. These three nerves, after leav- 



