582 PROCEEDINGS OF THE NATIONAL MUSEUM 



42 



Figure 13. — Acanthozoon nigropapilhsus, entire worm. (Explanation on page 597.) 



is evident. Behind the pharynx are plainly seen the two male pores 

 on hillocks, followed by the median female pore. The sucker, larger 

 than the hillocks around the gonopores, is conspicuous, located slightly 

 posterior to the middle. The convolutions of the uteri are seen to 

 either side in the postpharyngeal region. 



Differential diagnosis: The black color with black white- 

 tipped papillae is distinctive. 



Holotype: USNM 28661, m alcohol. 



Remarks: Marcus (1950) recommended revival of Acanthozoon 

 for pseudocerids with low dorsal elevations. Eveline Marcus (1955) 

 reduced Acanthozoon to a subgenus of Pseudoceros. However, if 

 Pseudoceros be defined as Pseudoceridae with a smooth dorsal surface 



