135 



EXTERNAl, CHARACTERS 



The length of the type specimen is 25 mm. The body is long, 

 slender, and in transverse section is circular in outline. The greatest 

 diameter is in the region of the clitellum, where it measures 0.57 mm. 

 The body is opaque and whitish yellow in the living specimen. Un- 

 fortunately the data concerning the number of somites have been lost, 

 and therefore that point must remain unsettled until additional ma- 

 terial is examined. The prostomium is rather blunt and rounded. 

 The intersegmental grooves arc rather indistinct. The shape and ar- 

 rangement of the setse are very much as in Henlea modcrata but 

 there is a distinct difference in the number of setae per bundle. In 

 the first thirteen somites the ventral bundles contain 6^8 setae, usually 

 the latter number; the lateral bundles contain 5-6, never more than 

 6. The mid region of the body usually has 7 setae in each of the 

 ventral bundles and 4-6 in the lateral iDundles. The proximal ends 

 of the setae are distinctly bent. 



INTERNAL CHARACTERS 



Brain. — The brain is in I and II, chiefly in the latter. The length 

 is about the same as the greatest width, the measurements being as 

 follows: length, 0.146 mm.; greatest width, 0.142 mm. The 

 posterior margin is distinctly emarginate and the anterior margin is 

 quite concave. The smallest width (0.125 mm.) is in the region 

 of the origin of the commissural trunks. From this point the lateral 

 margins diverge caudad as far as the region of greatest width, which 

 is about midway of the length of the organ. Thence the lateral mar- 

 gins round off gradually into the posterior margin. In transverse 

 section the brain is elliptical in outline. One pair of supporting strands 

 extends from the sides of the brain to the body wall; another pair 

 extends from the two terminal lobes to the body wall. 



Peptonephridia. — These organs are twO' rather complicated struc- 

 tures, one arising from the dorsal, and one from the ventral, surface 

 of the alimentary canal, in the anterior part of V. They resemble 

 those of H. modcrata in the general plan of structure, but present cer- 

 tain marked differences. The dorsal and ventral peptonephridia are 

 quite dissimilar. The dorsal one, at its origin, gives rise to two parts, 

 one ental and the other ectal. The ectal part is a large, thick-walled, 

 tubular structure, which extends into the body cavity. Immediately 

 beyond its origin this ectal part assumes a position parallel to the 

 digestive tract and extends caudad for about the length of one somite. 

 The ental part has a very intimate relation to the wall of the digestive 



