76 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 5 



Re-establishment of Stimpson's P. acuminatus gives equal and spe- 

 cific rank to the three organisms, asper {=transversus Stimpson), pana- 

 mensiSj and acuminatus, as conceived by Stimpson, rather than as forms 

 of a single species, as suggested by Rathbun, Diagnostic characters are 

 as follows : 



( 1 ) P. asper: Anterolateral arc broad, teeth showing little reduction ; 

 lateral spine equal to width of 4 or 5 adjacent teeth; cheliped 

 heavy, 2^^ times carapace length. 



(2) P. panamensis : Anterolateral arc narrow {Achelous-XWt) , teeth 

 2, 4, and 6 showing reduction; lateral spine equal to width of 

 2J^ to 3 adjacent teeth; cheliped heavy, 3 times carapace length 

 in male, 2^ in female. 



(3) P. acuminatus: Anterolateral arc broader than panamensis, 

 though not as broad as asper, teeth 2, 4, and 6 showing reduc- 

 tion; lateral spine equal to width of 6 or 7 adjacent teeth; cheli- 

 ped fragile, length 3 to 3^ times carapace in male, height of 

 manus % or i/^ times length of chela. 



XANTHIDAE 



Genus PLATYXANTHUS A. Milne Edwards 



Platyxanthus balboai, new species 

 Plate 20, Figs. 1-8 



Type: Female, holotype. Cat. No. 392, Allan Hancock Foundation, 

 The University of Southern California, and male, allotype, from out- 

 side Medidor Island, Bahia Honda, Panama, 30-35 fathoms, rock, mud, 

 and dead coralline; March 28, 1939; collected by Allan Hancock Expe- 

 dition of 1939 at Velero Station 948-39. 



Measurements: Female holotype: length of carapace 26.8 mm., width 

 30.8 mm. Male allotype: length of carapace 31 mm., width 36 mm., of 

 fronto-orbit 9.5 mm., of front 4.6 mm., length of major cheliped 60 mm., 

 of chela 49 mm., of dactyl 22 mm., height of manus 19 mm., of gape 

 4.7 mm. 



Diagnosis: Carapace narrow, convex, lumpy, proportion of length 

 to breadth 6:7. Front advanced, quadrifid, well separated from orbit, 

 frontal teeth tuberculiform. Four anterolateral teeth beside the exorbital. 

 Merus of outer maxilliped longer than broad, pentagonal ; ischium deeply 

 furrowed. Chelipeds of male grossly disproportionate, major chela ap- 

 proaching half of carapace displacement. Epistome and antennular areas 



