346 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



tooth. Ambulatory legs slender, covered with curled hair; distal artic- 

 ulations of merus acute, in first pair spiniform. (Rathbun, 1925, modi- 

 fied) 



Material examined: Juan Fernandez Island, Chile, Hassler, 1872, 

 M.C.Z. No. 2048, 2 males, 1 female. Also Paramithrax peroni, New 

 Zealand, L. R. Richardson, 1 pair. 



Measurements: Male holotype: median length 16.3 mm, length to 

 tip of horns 20.8 mm, width without spines ca. 12.8 mm, with spines 

 14.0 mm. Ovigerous female: length to tip of horns 12.3 mm. Male 

 specimen, M.C.Z. No. 2048: median length 16.1 mm, length to tip 

 of horns 20.2 mm, width without spines 13.2 mm, with spines 14.8 mm, 

 rostrum 4.8 mm, basal width 3.7 mm, cheliped 20.4 mm, chela 11.7 mm, 

 dactyl 5.6 mm, height of palm 4.7 mm, walking legs 21.6, 19.8, 16.6, 

 and 14.6 mm, respectively. Mature, non-ovigerous female: length 13.9 

 mm, width including spines 10.3 mm, without spines 9.5 mm. 



Color in life: Unknown. 



Habitat: Not specified. 



Depth: Not given. 



Remarks: Through the kindness of Professor L. R. Richardson of 

 Victoria College, Wellington, specimens of Paramithrax peroni were 

 made available for study. These serve to confirm the differences noted by 

 Rathbun (1925, p. 240) between New Zealand and Juan Fernandez 

 specimens, including the absence in Paramithrax peroni of the preorbital 

 spine, the absence in P. baeckstroemi of the second of the four branchial 

 spines, and the more elaborate ornamentation of the carpus of the cheli- 

 ped in the latter species. In addition to these points, and to such consid- 

 erations as the disparity in size of mature specimens and the remoteness 

 of their habitats, we have now the distinctness of their gonopods, here 

 illustrated (Plate U, figs. 1, la; 2, 2a), as a basis for treating them as 

 separate species. 



Subfamily MlTHRAGINAE 



Majinae Alcock, 1895, pp. 161, 166, and 236 (part: the Periceroida). 

 Mithracinae Balss + Macrocoelominac Balss, 1929, pp. 16, 20. 



Carapace broadened anteriorly by the outstanding, often tubular, 

 orbits ; the orbits formed ( 1 ) by an arched supraocular hood, or semi- 

 tubular horn, (2) by a hollowed postocular process, and (3) by a re- 

 markable broadening, or by a prolongation, of the anterior part of the 

 basal antennal article, affording complete concealment to the retracted 

 eye. Rostrum often more or less deflexed. (Alcock) 



