630 



Bulletin American Museum of Natural History 



[Vol. XLVIII 



Measurements. — Male holotype, length of carapace 14, greatest width 15.8, 

 width between outer orbital angles 14.4 mm. 



Description. — Dorsal aspect very much as in Hemigrapsus oregonensis. In 

 specimens of equal carapace length, the width is a little less, both at the widest part 

 and at the orbital angles, than it is in oregonensis, the posterior of the lateral teeth is 

 smaller, the granulated ridge setting off the steep postero-lateral region is fainter, the 

 blunt ridge just above and parallel to the margin of the front is more extensive, 

 punctate and smoother than in oregonensis. 



The most noticeable difference in the species is in the outer maxillipeds; the 

 ischium is distinctly smaller than the merus and diminishes in width from the distal 

 to the proximal end, its distal margin is concave forward except for a smooth arcuate 

 lobe at the inner end which is strongly produced forward and partially overlaps the 

 merus; merus elongate; palpus strongly developed, reaching, when it is folded in 

 place, quite to the ischium. 



Fig. 7. Goetice americanus, left outer maxilliped of d 1 paratype (Cat. No. 

 17452, U. S. N. M.), X 8. 



The chelipeds in the well-developed male are very heavy and equal; palms high 

 height greater than length measured from articulation with carpus to sinus between 

 fingers; anterior margin of palm very oblique; tip of immovable finger curved up- 

 ward, wider than tip of dactylus; dactylus slender, a large lobe near its base, the distal 

 half of which has a crenulated edge, continued also along the edge of the dactyl as far 

 as the tip; a large brush of coarse hair occupies the greater part of the inner surface 

 of the palm. 



Ambulatory legs of moderate size and bordered with long, soft hair. 



Abdomen of male narrow, the sides converging little from the third to the middle 

 of the sixth segment. 



Variation. — There is considerable variation in individuals from the same locality. 

 Large specimens have not always as well developed chelipeds as smaller specimens. 

 The two chelipeds may be unlike, one with a tooth on the dactyl, the other without a 

 tooth, and with meeting fingers, similar to those of females and young. Most of the 

 specimens of the type lot including all the females are devoid of hair on the legs; 

 in a lot from Guaymas, there is a greater proportion of hairy individuals, including 

 some females. 



