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U.S. NATIONAL MUSEUM BULLETIN 260 



pleonal epimeron the new subspecies (not the juvenile) resembles 

 Acidostoma laticome Sars but it differs from that species by the 

 straight dorsal margin of pleonite 4, the straight (not hooked) dactyl 

 of gnathopod 2, by the longer and more deeply cleft telson, and the 

 shorter palp article 4 of the maxilliped. 



Figure 17. — Acidostoma obesuni ortiim, new subspecies, juvenile, 2.8 mm, 7231: a, anterio- 

 end, left lateral; b, pleon; c,d, antennae 1,2; ej, maxillae 1,2; g,h, mandibles; i, uropod 3. 

 /, maxilliped, showing folding lines on outer plate. 



Acidostoma pectinatum Gurjanova (1962) has a distinctively sub- 

 castellate dorsal peduncular margin on uropod 2 and numerous other 

 differences from A. obesuni. Acidostoma inolariferurn Margulis 

 (1963) and A. hancochi Hurley (1963) have short, broad telsons and 

 stronger teeth on the third pleonal epimeron than does the new sub- 

 species. 



