60 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



numerous nephridia are present in most segments. The following: 

 classification follows that of Bahl (1924, 1926, 1950). 



The integumentary nephridia are extremely small, ranging from 

 0.25-0.5 mm. in length, and are scattered over the interior face of the 

 body wall in all but the first two segments. As no collecting funnel is 

 present and each nephridium communicates directly to the exterior 

 through its nephridiopore, they are termed exonephric micronephridia. 

 In P. hupeiensis there are about 175 such micronephridia per segment 

 in the region posterior to the intestinal caeca. 



The septal nephridia are distributed over the anterior and posterior 

 faces of all septa behind 15/16, close to the body wall. The nephro- 

 stome is well developed, consisting of from 10 to 12 marginal cells com- 

 posing a funnel and sLx closely compacted cells forming the ventral lip. 

 The excretory products, carried by a series of collecting ducts, are 

 discharged into the gut. The septal nephridia are classified as entero- 

 nephric meganephridia. There are 70 to 80 such meganephridia per 

 segment in the region just posterior to the caeca. 



The pharyngeal nephridia, which lack collecting funnels, are entero- 

 nephric micronephridia. They are composed of large masses of inter- 

 connected nephridia scattered over the lateral pharyngeal walls. 

 Excretory products are discharged from the collecting ducts into the 

 lumen of the pharynx. 



Discussion: In all major respects the Pelham population of P. 

 hupeiensis is in taxonomic agreement with the type specimen as de- 

 scribed by Michaelsen. The first dorsal pore of the type is located 

 at intersegmental furrow 12/13, while it was found at 11/12 in aU the 

 Pelham animals. The pair of intestinal caeca which occur either in 

 segment 27 or 28 in the Pelham worms is recorded in segment 26 of 

 the type. Size variations are of course to be anticipated because of 

 nutritional differences, etc., as is the relation between absolute size 

 and the degree of sexual maturity. Segment and setal numbers show 

 a narrow range of variation considering their large numbers. The 

 spermathecal ampulla and diverticulum may or may not penetrate 

 adjacent septa, but as the position of the external pores is constant, 

 their internal arrangement is of minor importance. 



The Pelham population shows a high degree of uniformity. Only 

 the position of the caeca was subject to meristic translocation and, 

 except in one specimen which possessed a supernumerary female pore, 

 no homoeotic duplications were observed. P. hupeiensis is in close 

 taxonomic agreement with its genus, its species characters falling 

 within the generic range of variability as given by Stephenson 

 (1930). 



Diagnostic characters: External: Color pale green to deep olive 

 with a distinct purple or black line on the dorsal midline extending 

 from the posterior margin of the clitellum to the anal segment. 



