THE CANCROID CRABS OF AMERICA 179 



INDETERMINABLE SPECIES 



Cancer amoenus Herbst, Naturg. Krabben u. Krebse, vol. 3, 1799, p. 64, 

 pi. 49, fig. 3 (tj'pe-locality unknown; type not extant). 



NOMEN NUDUM 



Pirimela chilensis Philippi, Zool. Anzeiger, vol. 16, 1894, p. 264. Probably a 



young Cancer. 



KEY TO THE AMERICAN SPECIMENS OF CANCER 20 MM. AND LESS IN WIDTH M 



A'. Antero-lateral and postero-lateral margins meeting at a distinct angle. 

 Carapace widest at ninth or tenth antero-lateral tooth. 

 B'. Carapace widest at tenth and last antero-lateral tooth; postero-lateral 

 margin unbroken, entire. Carpus of cheliped with a single spine above, 



at distal angle; fingers light colored magister, p. 222. 



B2. Carapace widest at ninth antero-lateral tooth. 



C^ Branchial regions not nearly meeting on median line. 

 D^ First postero-lateral tooth prominent. 



E'. First postero-lateral tooth usually spiny pointed, never 



broadly rounded. 



F'. Carpus of cheliped with two prominent spines (not 



counting that at articulation), one spine above at 



distal end and the second below it at inner angle. 



G'. First postero-lateral tooth projecting laterally 



beyond carapace as seen from above. Carapace 



comparatively smooth, without pubescence. 



Fingers without dark color gracilis, p. 219. 



G^. First postero-lateral tooth projecting dorsally, 



not reaching beyond outline as seen from above; 



carapace hairy, rough; antero-lateral teeth spiny 



pointed. Fingers with color across middle, 



tips light. 



H^. Antero-lateral teeth conspicuously alternating 



large and smaU. A tooth at middle of 



supra-orbital margin. Outer maxillipeds 



fitting in buccal cavity branneri, p. 2JI. 



H2. Antero-lateral teeth very long, denticulat-e, 

 slightly alternating in size. A rounded lobe 

 at middle of supra-orbital margin Outer 

 maxillipeds overreaching epistome. 



polyodon, p. 202. 

 F^. Carpus of cheliped with only one prominent spine oa 

 inner side that at distal end. 

 G'. A tooth at middle of supra-orbital margin. An- 

 tero-lateral teeth prominent, curved forward. 

 Sometimes an inconspicuous spine present at 

 inner angle of carpus. Fingers mostly dark, 



tips light antennarius, p. 210. 



G-. Middle of supra-orbital margin truncate. Antero- 

 lateral teeth shallow. Distal half of fingers 

 light brown except tips which are whitish. 



borealis, p. 182 

 E2. First postero-lateral tooth broadly rounded, never spiniform. 

 a second tooth usually present. 



23 Young of C. luederwaldti not known. 



