An American Eavthico)in of the Family Phreorijctichr. 113 



The change to the distinctive cell of the fatty body and the 

 fully developed bi-lobed, ciliated funnel is gradual, becoming 

 complete in the fifteenth segment, where, however, the fatty 

 bodies are still very small, occupying only the anterior part of 

 the ccelom. In the posterior somites, on the other hand, the 

 nephridia and the fatty bodies are very large, occupying the 

 greater part of the co'lomic space. There was no trace of sex- 

 ual organs in any of the specimens studied. 



Just behind the tip of each seta is a small oval mass of 

 cells resembling a gland (PI. VI., Fig. 2) and opening to the 

 surface at the very margin of the setal sheath. The first dis- 

 sepiment occurs between the fourth and fifth segments. The 

 ctelomic fluid is remarkably destitute of leucocytes. 



The pharynx is short, thick-walled, with heavy roughened 

 cuticle, thick, circular and rather few and stout radiating mus- 

 cles. A broad, low median ridge projects fromthe dorsal wall 

 of this cavity. The oesophagus extends through segments one 

 to three. It is thin-walled in the first two somites, with a thin 

 cuticular lining and scarcely any circular muscular fibers, but 

 very numerous slender radiating muscles extending to the body 

 wall. In the third somite its structure is similar, except that 

 it is provided with a very thick circular muscle and that the 

 radiating muscles are first reduced in number and then disap- 

 pear. The cuticle is also thicker than that of the preceding 

 part. With the fifth somite the intestine suddenly begins, the 

 muscular wall becoming very thin and the epithelial cells very 

 long and highly and irregularly villose in arrangement (PI. 

 VII., Fig. 11). Here also begin the chlorogon cells in a thin 

 imperfect layer. The villosities become at first more prominent 

 and irregular backwards, but at about the fifteenth to the twen- 

 tieth segment are gradually reduced in length, the epithelial 

 lining becoming more uniform in thickness. The intestine is 

 slightly constricted at the dissepiments, and there also the 

 epithelial cells are considerably shortened (PI. VIII., Fig. 12). 

 The exposed ends of the cells are densely ciliated. The intes- 

 tinal wall contains capacious blood sinuses which connect at 

 intervals with the dorsal vessel (PI. VIII., Fig. 12). In the 

 posterior part of the alimentary canal the epithelial cells 

 are very much elongated, and the lumen of the canal small. 



