92 Rathbun Synopsis of the American Sesarmse. 



greater than the anterior; the width of the ambulatory legs is also vari 

 able, but as a rule the meri are shorter than in S. roberli. 



Distribution. Abaco and San Salvador, Bahamas ; Swan Island, Carib 

 bean Sea (U. S. Nat. Mus.). Destero, Brazil (Paris Mus.). Rio de Janeiro ; 

 Rat Island, Monte Video, type locality (Brit. Mus.) 



Sesarma (Holometopus) haiiseni Rathbun, new species. 



Carapace much broader than long, broader anteriorly than posteriorly. 

 Regions well marked ; mesogastric very wide behind, and with a curved 

 sulcus parallel to its posterior margin. Surface smooth and punctate and 

 without granulations. Superior margin of front uneven, the inner lobes 

 sloping backward from the middle. Front more than 4 times as wide as 

 high ; margin projecting, thin, arcuate in a front view, slightly sinuous in 

 a dorsal view. Terminal segment of abdomen broader than long. Appen 

 dages narrow and with slender curved tips. 



Merus and carpus of chelipeds with outer surface covered with broken 

 rugose lines ; margins denticulate. Hand deep, covered with depressed 

 tubercles ; superior margin with a thin denticulate crest. Fingers irregu 

 larly toothed; the largest tooth of the dactylus is midway of its length, 

 and fits between the two largest teeth of the pollex. The meri of the 

 ambulatory legs are less than 2% times their width. 



Dimensions. $ : Length, 13.5 mm.; exorbital width, 16.6; posterior 

 width, 15.5; superior frontal width, 9.5; depth of front, 2; length of 

 merus of fourth ambulatory leg, 8; width, 3.7. 



Type locality. West Indies, one r? (Copenhagen Mus.). 



Dedicated to Dr. H. F. Hansen. 



