178 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



Ambulatory legs moderately long and slender, cylindrical, first leg of 

 male exceeding second by length of its propodus and dactylus, remaining 

 legs decreasing in order. Six clusters of hooked hairs along the margin 

 of leg one, three meral, two carpal, and one propodal; a single clavate 

 hair at apex of each condyle. Dactyls strongly curved, dentigerous, tips 

 corneous. 



Male abdomen with seven free segments, sides straight and converg- 

 ing, segments two to six with a median setose tubercle, segment seven 

 triangular. Male first pleopod with a fold along convex margin terminat- 

 ing in a square-cut flap concealing orifice; a row of papillae along con- 

 cave margin. 



Material examined: Supplementing the holotype and two paratypes 

 from station 303-34 are 6 specimens from 4 additional Clarion Island 

 stations. (See Table 31) 



Remarks: The series of Tyche obtained by the Velero III during 

 two brief stops at Clarion Island in June, 1934, and March, 1939, con- 

 sisting of 5 male and 4 female specimens, compares more than favorably 

 with the 3 males, one female, and 2 young taken on four separate Han- 

 cock cruises to the Galapagos Islands. Clarion Island specimens were 

 recognized at once as differing from Galapagos Island specimens, but 

 it is only through studies recently completed that it has been possible to 

 differentiate them successfully from Gulf of California-Bay of Panama 

 specimens. Examination of maxillipeds and male first pleopods of all 

 available material, Atlantic as well as Pacific, has revealed important 

 differences which can be correlated with geographic distribution. It is 

 not surprising, therefore, that the most striking of these should occur 

 among Clarion Island and Galapagos specimens, where isolation is 

 extreme and endemism highly developed. 



Tyche galapagensis, new species 

 Plate J, Fig. 6 



Tyche lamellifrons, Garth, 1946, p. 406, pi. 54, figs. 1-6. Not T. lamel- 

 lifrons Bell. 



Type: Ovigerous female, holotype, Cat. No. 100917, U. S. National 

 Museum, from Albemarle Point, Albemarle Island, Galapagos Islands, 

 shore, February 11, 1933, collected by Allan Hancock Expedition of 

 1933 at Velero III station 69-33. 



Measurements: Female holotype: length of carapace 27.7 mm, width 

 17.9 mm, distance from gastric tubercle to posterior margin 15.5 mm, 

 length of rostrum 4.6 mm, width 3.8 mm, length of cheliped 19.5 mm, 



