58 Illinois State Laboratory of Natural Histortj. 



the sheets. The whole structure is folded upon itself in an 

 irregular fashion, and its free edges may be very ragged from 

 the tearing apart of the extremities of series of ova. 



The oviducts may be found posterior to and opposite the 

 ovaries in somite 13. Their free internal portions are trumpet- 

 shaped structures having, when under the microscope, the 

 appearance of a miniature calla lily. Behind the flared 

 internal aperture the ducts are narrowed, and, passing through 

 the dissepiment between somites 13 and 14, penetrate the 

 body-wall in the anterior part of somite 14. 



The Nervous System. 



The cerebral nervous mass is very small as compared with 

 that of Lumbricus and AUolobophora, and is correspondingly 

 simple. It lies upon the pharynx, in somite 2, and is a slender, 

 transversely elongated body, with a slight median anterior and 

 and posterior impressed line of division between the two fused 

 ganglia composing it. Its greatest diameter is less than a 

 fourth of its length. As it lies in position it forms an arch, 

 with the convex side posterior. Its surface is perfectly 

 smooth, and no nerves arise from it except two large cords 

 which supply the region about the mouth and arise one at each 

 of its outer extremities. Numerous small white cords which 

 are liable to be mistaken for nerves arise from its dorsal and 

 ventral posterior surfaces, and extend posteriorly towards the 

 skin, but their iridescence in sunlight shows them to be small 

 bands of muscle. 



Strong commissures extend obliquely down the sides of the 

 pharynx from the extremities of the brain to the sub- 

 pharyngeal ganglia in somite 3. A little ventrad of the brain 

 each commissure gives off from its anterior edge a large 

 nerve which extends forwards along the pharynx, parallel with 

 the nerve arising from the extremity of the brain. Two other 

 small cords also arise from the anterior edge of each commis- 

 sure; one near the ventral end of the dorsal third of its length, 

 the other near the dorsal end of the ventral third. The com- 

 missures gradually expand as they apjiroach the first ventral 

 nervous mass, their inner edges with the anterior edge of the 



