388 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 5 



C^ Carapace paved with smooth, flat granules; rostrum 



tuberculate ; size large . . . M. (Mithrax) bellii 

 C^ Carapace with 2 rows of lateral marginal spines, rostrum 



subtruncate ; size small . . M. (Mithrax) pygmaeus 

 h? Carapace with oblique branchial furrows (Subgenus Mithraculus) 

 B^ Three large anterolateral lobes; inner margin of entire 



cheliped laminated . . . M. (Mithraculus) nodosus 

 B2 Two acute tubercules and a spine on anterolateral margin ; 



carpus only of cheliped, laminated 



M. (Mithraculus) denticulatus 



Subgenus Mithrax 



Mithrax (Mithrax) spinipes (Bell) 



Plate 65, Figs. 5, 6 



Pisa spinipes Bell, Proc. Zool. Soc. London, vol. 3, p. 171, 1835 (1836) ; 



Trans. Zool. Soc. London, vol. 2, p. 50, pi. 9, figs. 6, 6s-u, 1836. 

 Mithrax (Mithrax) spinipes Rathbun, Bull. 129, U.S. Nat. Mus., p. 391, 

 pi. 136, figs. 3 and 4; pi. 262, fig. 5, 1925. Boone, Zoologica, vol. 8, 

 no. 4, p. 154, fig. 48, 1927. Sivertsen, Med. fra det Zool. Mus., Oslo, 

 nr. 38, p. 12, 1933. Crane, Zoologica, vol. 22, no. 3, p. 60, 1937. 

 Mithrax (Mithrax) mexicanus Glassell, Zoologica, vol. 21, no. 17, p. 

 213, 1936. 



Type localities. — Galapagos Islands, 16 fms; Santa Elena, 6 fms. 

 Types. — Not extant. 



Range. — From Gulf of California (Albatross) to Santa Elena, Ecua- 

 dor, and the Galapagos Islands (Bell) ; 2^-33 fms. 

 Atlantic analogue. — M. acuticornis Stimpson. 



Diagnosis. — Based on immature specimens: carapace elongate oval, 

 spinulous, rostral horns long and divergent. A series of anterolateral 

 spinules which develop into 5 lateral spines in the adult. Paired meso- 

 gastric tubercles of adult not always apparent in young specimens. No 

 lateral angle, as in older specimens. 



Material examined (3 specimens from as many stations). — 

 155-34. Tagus Cove, Albemarle Island, 50-60 fms, Jan. 15, 1934, 1 



male. 

 814-38. North of Hood Island3-40 fms, Jan. 28, 1938, 1 male (pho- 

 tographed). 

 817-38. North of Hood Island, 140-160 fms, Jan. 29, 1938, 1 male. 

 Measurements. — Young male: length 11.3 mm, width 6.5 mm. 



