Boone, Crustacea, Cruises of "Ara" and "Alva" 241 



Subfamily: Sesarminae 



Genus: SESARMA Say 

 Sesarma (Sesarma) rotundatum Hess 



i 



Plate 96 



Type: Herr Hess described this Sesarma in 1865 from a 

 specimen collected in Sydney, New South Wales, and deposited 

 in the Gottingen Zoological Museum. 



Material examined: One male, collected on Kusai Island, 

 Caroline Islands. 



Distribution : TTiis very active little crab of the littoral zone 

 of the Indo-Pacific probably has a much wider and more aoundant 

 distribution than is indicated by published records, the paucity 

 of the latter probably being due to the agility and speed the crab 

 shows in escaping collectors. The following records for it have 

 been pubhshed: Sydney, New South Wales (Hess) ; Philippines 

 (de Man) ; Seleo, Berlinhafen, New Guinea (Nobili) ; Eastern 

 Seas, Duke of York Island, Nairai, Fiji Islands (Miers) ; Funa- 

 futi, Ellice Islands, and Rotuma (Borradaile) ; Aru Atoll and 

 Ebon, Marshall Islands (Rathbun) ; Upola, Samoa (Milne Ed- 

 wards) ; Kusai Island, Caroline Islands (Boone) ; and Oahu, 

 Hawaiian Islands (Rathbun). 



Technical description: This single specimen from Kusai 

 Island is a male, the carapace of which measures 42.5 millimeters 

 long and 45.5 millimeters wide ; the longest ambulatory measures 

 100 millimeters total length, with the meral joint 32 millimeters 

 long and 10 millimeters greatest width. The carapace is longitu- 

 dinally convex on the anterior half, also on the entire lateral areas, 

 the four post-frontal lobes being prominent, unequal, beaded. The 

 regions of the carapace are distinctly defined, the protogastric 

 aerolations being tumid, separated from the anterior branchial 

 areas by a wide cervical groove which terminates anteriorly in a 

 deep depression behind the orbit and is posteriorly confluent with 

 the deep-pitted urogastric depression. The mesogastric, cardiac 

 and intestinal regions are separately circumscribed; the epi- 

 branchial regions are convex, with the oblique striations, charac- 

 teristic of this genus, faintly but definitely outlined in the Kusai 

 specimen. The deflected region is 18 millimeters long, 6 milli- 



