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U.S. NATIONAL MUSEUM BULLETIN 260 



The differences between the specimens at hand and the specimen of 

 Schellenberg are presumably not attributable to differences in sex or 

 size, for the largest specimen at hand is 28 mm long and thus approxi- 

 mates that of Schellenberg; even though it is a male, and Schellen- 

 berg's a female, the family Stegocephalidae is not known to have such 

 extreme sexually dimorphic conditions. 



Figure 69.— Parandaniexis mirabilis Schellenberg, male, 28.0 mm, Baja Slope Expedition 

 Sta. P 285-61, lateral view of animal. Parts surrounding body are setae and hooks of 

 sabellid and polynoid polychaetes found in alimentary tract of amphipod. 



The prehensile character of pereopod 2 is unusual for Stegocephali- 

 dae but is reminiscent of similar conditions in various pelagic Lysian- 

 assidae suspected of being commensals with salps and tunicates. The 

 benthic and not pelagic character of Parandaniexis mirabilis is, how- 



