1907 



NATURAL SCIEN-CES OF nilLADELPHIA. 



123 



dium, the inner or mesial edge frequently extending to meet and fuse 

 with its fellow of the opposite side. One or two nuclei are seen to lie 

 in this portion of the nephriilium. Within its substance, near its ectal 

 margin, beginning near the anterior limit of the second trunk segment 

 and running parallel to the long axis of the body, is a canal, the inner 

 canal of the nepliiidium (text fig. IV, figs. 25 and 26, i.c.n.), its anterior 

 end conical and terminating blindly in the protoplasm. This canal is 

 lined with long cilia directed caudad, and has a maximum calibre of 



Fig. IV. — Nephridinm of the first pair, belonging to the left side, as seen from 

 the interior of the body. Reconstructed from sections. X 1053. For ex- 

 planation of reference letters see Explanation of Plates. 



about 3 fi. Xear the middle of the second segment the inner canal 

 contracts rather suddenly to about one-third or one-fourth of its former 

 diameter, and sends off a slender connecting branch to the lateral 

 glandular portion of the nephridium (text fig. IV, figs. 2oc-e, and fig. 

 26, l.g.n.). The latter is a large flat biscuit-shaped mass of protoplasm, 

 irregularly lobed or incised, and pressed closely against the lateral 

 body wall. On its mesial side it is in contact with the salivary gland 

 (s.gl.). Within the lateral glandular portion are three or four large 

 spherical nuclei, containing very large karyosomes. No cell boundaries 

 are visible. The cytoplasm has a coarsely granular appearance and 

 stains very densely. The whole mass is permeated throughout by a 



