404 BULLETIN" 129^ UNITED STATES NATIONAL MUSEUM 



Young. — The young presents such a different aspect from the adult 

 that it might easily be mistaken for another species. The carapace 

 is narrower; the width may be less than the length. The body and 

 legs, but not the chelae, are everywhere covered with a furry hair. 

 The protuberances are all sharp-pointed; the rostral horns curve 

 toward each other; the pair of spines at the base of the horns are 

 nearly as long as the horns and are divergent, while the next pair is 

 very small.^- 



Color. — Adult, deep purplish brown, young, light brown (Bell). 



Habitat. — Sand}^ mud (Bell). 



Measurements.— Male (25672), entire length of carapace 63.6, 

 width 65.4 mm. Young female (33386) , entire length of carapace 

 21.7, width 20.7 mm. 



Range. — Galapagos Islands, shore to a depth of 6 fathoms (Bell). 

 Chile (Miers). 



Material examined. — Chatham Island, Galapagos Islands; shore; 

 January 8, 1905; Albatross; 1 young female (33386). 



Black Bight, Albemarle Island, Galapagos Islands; Stanford Univ.; 

 1 male (25672) . 



Eden Island, off Indefatigable Island; in rock pools; April 6, 1923; 

 Williams Galapagos Exped. ; 1 young male (57563) . 



Galapagos Islands; Hassler Exped.; 2 young males (1966, M. C. Z.). 



MITHRAX (MITHRAX) BRAZILIENSIS Rathbun 



Plate 147, fig. 1 



Mithrax braziliensis Rathbun, Proc. U. S. Nat. Mus., vol. 15, 1892, p. 268, 

 pi. 36, fig. 2 (type-locality, Mar Grande, Bay of Bahia, Brazil; holotype, 

 Cat. No. 19952, U.S.N.M.); Proc. Washington Acad. Sci., vol. 2, 1900, 

 p. 143. 



Mithrax verrucosus Rathbun (not Milne Edwards), Proc. Washington Acad. 

 Sci., vol. 2, 1900, p. 142. 



Diagnosis. — Size small. Carapace nearly smooth above, four 

 antero-lateral spines or spines and tubercles. Horns several times 

 broader than long. 



Description. — -Carapace broader than long, ovate, rather evenly 

 convex, and in the fully developed specimen nearly smooth dorsally, 

 the regional sulci being faint except at the middle of the carapace. 

 Rostrum very short and broad, the anterior margin of each lobe 

 about three times as long as the depth of the median emargination. 

 In the very young, the sinus is much wider and the lobes corres- 

 pondingly narrower. Preorbital lobe large, blunt, not projecting, 

 being less advanced than any of the three lobes of the antennal 

 segment. Lobes of orbital margin eight, including two small, 

 shallow, supraorbital lobules, one at the outer angle and two below, 



" Rathbun, Mem. Mus. Comp. Zool., vol. 35, 1907, p. 74. 



