476 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



g^. Plates of supporting ribs numbering up to 30 or 

 more ; knob present on anterior surface of first 

 autennae ; second maxillae slender ; salt water, 



Pacific coast melanostictus (p. 487) 



ff'. Plates in supports numbering about 15 to 20; 

 carapace reaching abdomen ; anterior hook pres- 

 ent on first antennae. 

 7t\ First two swimming appendages with fiagella ; 

 second maxillae short and stout with spinous 

 pads on ventral surface, postmaxillary spines 

 short and truncate ; antennae short ; salt water. 



Pacific coast ? pugettensis (p. 487) 



If. First two swimming appendages without fiagella ; 

 second maxillae about normal in size, proximal 

 tooth on basal plate broader, two pairs of 

 postmaxillary spines not truncate; second an- 

 tennae longer; salt water. Key West — floridensis (p. 489) 

 f. Suction cups supported by an elongate proximal seg- 

 ment and imbricate plates. 

 g^. First two pairs of swimming appendages without 

 fiagella. 

 h^. Respiratory areas small and widely separated; 

 proximal segment in ribs of suction cups 

 elongate and narrow ; posterior lobe of fourth 

 appendages of female somewhat bilobed; ante- 

 rior knob present on first antennae ; salt water, 



British Columbia borealis (p. 490) 



h!^. Respiratory areas normal (one large and one 

 small). 

 i\ Maxillary spines about alike, posterior respira- 

 tory area large and irregular in shape ; swim- 

 ming lobe on posterior surface of fourth 

 appendages boot-shaped on female; salt 



water megalops (p. 492) 



i". Lateral spine on basal plate of second maxillae 



blunt, other two more pointed; anal sinus 



deep. 



;\ Suction cups occupying almost full width of 



carapace, supporting ribs composed of 6 to 



10 imbricate plates and a rectangular basal 



segment ; spine on ventral surface of hook 



inconspicuous, all others broad; posterior 



respiratory area reaching close to anterior 



one and about same width for its full 



length ; salt water bicolor (p. 517y, 



f. Suction cups normal, supporting ribs composed 

 of 6 or 7 imbricate plates (12 to 14 on 

 female) with rectangular basal segment; 

 spine on ventral surface of hook prominent, 

 postantennal spines larger than others; 

 posterior respiratory area some distance 

 from anterior one, anterior half narrower 

 than posterior portion; salt water fuscus (p. 518) 



