162 U.S. NATIONAL MUSEUM BULLETIN 271 



2 and 3 coalesced; mouthparts basic, lower lip lacking distinct inner 

 lobes; gnathopods small, subchelate; uropod 3 biramous; telson of 

 medium length, cleft. 



Relationship. — The Ampeliscidae have cuticular visual lenses 

 and pereopod 5 is shorter and of different structure than pereopod 4. 

 Other nonisaeid families with coalesced urosomites 2-3 are the Dexa- 



FiGURE 67.— Atylidae: a, Atylus falcatus Metzger (Sars, 1895, pi. 164); b, Atylus carinatus, 

 (Fabricius) (Sars, 1895, pi. 166). 



