NO. 1788. NORTH AMERICAN ERGASILIDJi!— WILSON. 367 



Mursense (Brian, 1906) is made the type of the provisional new genus Phagiis (see 

 p. 391). Ostracionis (Richiardi, 1870) is transferred to Brian's genus Anchistrotos. 

 Finally there are two species, viinimus and oblongus (Richiardi, 1880) which have 

 never been described, and hence can not be definitely located at the present time. 

 a. Maxillipeds turned forward outside of the other mouth-parts, with the basal joint 



fused to the ventral surface of the head, females b. 



a. Maxillipeds in normal position behind the other mouth-parts, both joints free and 



of the usual shape, males I. 



b. Terminal claw on maxillipeds very stout, with one or more teeth or branches 

 and turned backward along the central axis of the basal joint in a sigmoid 



curve c. 



b Terminal claw on maxillipeds slender, without teeth or branches, and usually 

 turned backward along the lateral margin of the basal joint, or even outside 



it, in a simple curve g. 



c. Exopod of first swimming leg with a single triangular joint, well armed with 



plumose setae d. 



c. Exopod of first swimming leg with two joints, the terminal one only armed with 



plumose setae c. 



c. Exopod of first swimming leg with three joints like the endopod, the two ter- 

 minal ones with plumose setaj /. 



d. Basal joints of first antennae close together; third joint only with tactile 

 hairs; first abdomen joint as long as the other two. 



eminens, new species, p. 368. 

 d. Basal joints of first antennae close together, each with one or two slender 

 tactile hairs; three abdomen joints the same length. 



bellones Burmeister, 1833. 

 d. Basal joints of first antennae widely separated, each with several stout spines; 



first abdomen joint as long as the other two megaceros Heller, 1865. 



e. Frontal margin well rounded, entirely covering the bases of the first anten- 

 na? and filling the space between them; mandible and second maxilla 



simple and smooth concinnus, new species, p. 371. 



e. Frontal margin well rounded, entirely covering the bases of the first 

 antennae and filling the space between them; mandible with a secondary 

 spine on the second joint; second maxilla bipartite, both appendages 



toothed nitidus, new species, p. 374. 



e. Frontal margin reentrant, showing the entire bases of the first antennae in 

 dorsal view; mandible and second maxilla simple and smooth. 



solex Claus, 1864, p. 375. 



/. First three free thorax joints nearly as wide as the cephalothorax ; fourth 



joint abruptly narrowed to one-third that width; maxillipeds with but 



a single plumose seta glyphisodoniis Kroyer, 1863. 



/. Only the first free thorax joint as wide as the cephalothorax, the second 

 narrowed to two-thirds, the third to one-third of that width; maxilli- 

 peds with three large plumose setae exilipes, new species, p. 377. 



g. Frontal margin of carapace deeply notched; basal joints of first antennae 

 fully visible and heavily armed with stout spines and digitate pro- 

 cesses h. 



g. Frontal margin of carapace pi'otruding and covering the bases of the 

 first antennae; the latter distinctly jointed and armed with short 



Betae, without spines or processes k. 



h. Maxillipeds with but a single plumose seta; carapace much wider 



than free segments i. 



h. Maxillipeds with two large plumose setae; carapace but little wider 

 than the first free segment j. 



