PART 1 GARTH : PACIFIC OXYRHYNCHA 355 



Species not treated because of insufficient data: 

 Mithrax (Mithrax) rostratus Bell (1835b, p. 171; 1836, p. 51, pi. 10, 



figs. 1, la, lb) ; type locality unknown; not collected since original 



description. Not Mithrax rostratus Boone (1930b, p. 1, figs, la, 



lb), which is Loxorhynchus grandis Stimpson. 

 Mithrax, species indeterminable, Rathbun (1925, p. 421); Valparaiso 



Bay, Chile, 25 fathoms, C. E. Porter; specimen returned to sender. 



Subgenus Mithrax Desmarest 



Mithrax (Mithrax) Rathbun, 1925, p. 383. 



Description: Carapace without conspicuous, smooth, oblique, bran- 

 chial sulci. Rostral horns usually as long as wide, sometimes elongate and 

 spiniform. Minor teeth or tubercles of orbit plainly marked, though 

 small. (Rathbun) 



The majority of west coast species belong in this, the more typical 

 division of the genus. 



Mithrax (Mithrax) tuberculatus Stimpson 

 Plate V, Fig. 3 ; Plate 40, Fig. 1 



Mithrax tuberculatus Stimpson, 1860b, p. 189. A. Milne Edwards, 1875, 

 p. 96, pi. 20, figs. 5, 5a, 5b. Miers, 1886, p. 86. Coventry, 1944, 

 p. 543. Not M. tuberculatus, Aurivillius, 1889, p. 57. 

 Mithrax (Mithrax) tuberculatus, Rathbun, 1925, p. 418, pi. 151, figs. 

 1, 2. Crane, 1937, p. 60. 



Type: 13 males and 13 females, cotypes, M.C.Z. No. 1228; 2 males 

 and 1 female, cotypes, U.S.N.M. No. 23178. Measured male cotype, 

 length 34.8 mm, width 42.4 mm. 



Type locality: Cape St. [San] Lucas, Lower California, Mexico; 

 John Xantus, collector. 



Localities subsequently reported, with collectors: Mexico: Arena 

 Bank, Gulf of California, Zaca (Crane) ; Mazatlan (A. Milne Ed- 

 wards) ; Maria Madre Island, Tres Marias Islands, Pioneer (Cov- 

 entry). Panama: Capt. Field (Rathbun). 



Atlantic analogue: Mithrax (Mithrax) hispidus (Herbst). 



Diagnosis: Rostral horns short and truncate, edges granulate. Two 

 lobes and a spine (or often two spines) on anterolateral margin. Areola- 

 tions of carapace granulate. Basal antennal article with two blunt teeth. 

 Two or three tubercles on inner margin of merus of cheliped. Male first 

 pleopod with pointed tip and two divergent subterminal flanges. 



