180 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



maxilliped, more than any other character, which sets the new species 

 apart from the species of Tyche heretofore known, requiring a modifica- 

 tion of the generic description as given by A. Milne Edwards.) 



Male cheliped noticeably stouter than ambulatory legs, merus 

 cylindrical, a proximal tubercle on superior surface; carpus smooth and 

 slightly compressed; manus moderately inflated, compressed, tapering 

 distally, palm smooth, fingers with a narrowly triangular gape at base, 

 denticulate to tips, tips crossing. 



Ambulatory legs short and stout in the female, longer and more 

 slender in the male. First leg of male longest of any, including the 

 cheliped, length greater than that of carapace and half again as great as 

 that of the succeeding member; remaining legs diminishing regularly in 

 size. All legs cylindrical, meri and carpi hairy, propodi of all except 

 the first bare, dactyli strongly curved, nondentigerous, and with corneous 

 tips. 



Male abdomen with seven free segments, a median setose tubercle 

 on all but the first and last; last segment narrowly triangular. Male 

 sternum flattened, a small tubercle opposite the last abdominal segment. 

 Female abdomen with seven free segments also. 



Male first pleopod curved at extremity, terminal opening triangular 

 in shape, protecting flap rudimentary, not extending to tip, the row of 

 papillae characterizing T. lamellifrons wanting. 



Material examined: Supplementing the holotype is a 24 mm male 

 from Sulivan Bay, James Island, Galapagos Islands, December 12, 1934, 

 Velero III station 343-35, from which measurements above were taken. 

 In addition, two males and two young, representing four additional 

 Galapagos collections, all reported in Garth (1946, p. 406) as Tyche 

 lamellifrons. 



Remarks: In connection with the present study the writer had oc- 

 casion to reexamine the Galapagos series of Tyche previously referred to 

 T. lamellifrons Bell (Garth, op. cit.). In the vial with an 18 mm male 

 from Post Office Bay, Charles Island, Velero III station 167-34, were 

 found two notes representing an exchange of comments between the 

 writer and the late Mary J. Rathbun which took place in 1935 : 



"Tyche, n. sp. (nee lamellifrons Bell). Preorbital horns not sub- 

 parallel but strongly divergent and exceeding rostral [horns] as in the 

 Atlantic species, emarginata. Secondary lobes of front almost coalescent. 

 Posterior margin faintly bilobate." (J. S. Garth) 



I think it is T. lamellifrons. We have one intermediate in size 

 between yours and the picture [of Bell's type?]. Its 4 anterior horns 

 are intermediate between those other 2." (M. J. Rathbun) 



