Anatomy and Histologij of a New Earthworm. 49 



The Set^. 



Four double longitudinal rows of setae with distances be- 

 tween adjacent rows nearly equal, are disposed along the ventral 

 face of the body. Each ordinary somite, therefore, bears eight 

 setae in four pairs. In sections, the two inner pairs of setae are 

 seen to be a little farther apart than each inner pair is from the 

 outer pair of the same side. A line drawn through the middle 

 of a somite at right angles to its vertical axis, would touch at its 

 extremities the outermost seta of both outer pairs. The setse 

 are thus confined to the ventral half of the body. Set* are 

 lacking upon somite 1 and upon the three or four terminal 

 posterior somites. They are of the usual form, but are rather 

 slender. The distal extremity is bent a very little, and is ob- 

 tusely pointed; the proximal end is bluntly rounded; the an- 

 gulate swelling at the proximate end of the distal third is 

 inconspicuous. In place of the inner pairs of ordinary setae, on 

 somites 18 and 20 are pairs of long uniformly curved copu- 

 latory setae. On somite 19 the two inner pairs of setae are 

 lacking. 



The Doksal Pores. 



The first dorsal pore is situated between somites 10 and 11. 

 These openings are elliptical in outline, and are transversely 

 placed. They may be obliterated in alcoholic specimens by the 

 contraction of surrounding tissues, but in worms killed in cor- 

 rosive sublimate they can be readily studied. 



The Clitellust'. 



The clitellug does not appear until the worms are nearly 

 grown, when the somites which will eventually bear the glands 

 assume a dull yellow color, but are not swollen beyond the 

 common outline. In large examples collected during the 

 month of May the clitellu^ is well developed. It is of a pale 

 flesh color, projects beyond the common outline a little, and 

 occupies the walls of somites 13 to 18 inclusive. Its surface 

 often presents peculiar fissures, which appear as if made by 

 passing the edge of a knife blade over it; the encircling rings 



