398 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



The male first pleopod of Microphrys triangulatus (Plate W, figs. 6 

 and 9) shows a prominent lateral swelling that is lacking in M. branchi- 

 alis (Plate W, figs. 7 and 8). When Galapagan M. triangulatus (fig. 

 9) and Lower Californian M. branchialis (fig. 8) are compared, how- 

 ever, the configuration of the apex is seen to be almost identical. Thus 

 the Galapagos Islands population of M. triangulatus inclines toward 

 M. branchialis, both from the standpoint of the male first pleopod and 

 of the lateral spine referred to in the paragraph above. 



Microphrys branchialis Rathbun 

 Plate W, Figs. 7, 8; Plate 44, Fig. 1 



Microphrys, sp., Rathbun, 1892, p. 254. 



Microphrys branchialis Rathbun, 1898, p. 577, pi. 41, fig. 5; 1910, p. 

 574 (part: not Galapagos) ; 1923b, p. 635; 1925, p. 502, pi. 176, 

 figs. 5, 6; pi. 270, fig. 1 ; text-fig. 143. Crane, 1937, p. 63. Schmitt, 

 1939, p. 9. Not Rathbun, 1902b, p. 285. 



Type: Male holotype, U.S.N.M. No. 21576, length 15.3 mm, width 

 including spines 14 mm, without spines 11.8 mm. 



Type locality: Magdalena Bay, Lower California, Mexico, 12 fath- 

 oms; Albatross station 2831. 



Localities subsequently reported, with collectors: Lower California, 

 Mexico: off Abreojos Point, 48 fathoms, Albatross (Rathbun, 1898); 

 Magdalena Bay, 10-15 fathoms, Houston (Schmitt); 13.5 fathoms, 

 Albatross (Rathbun, 1923b). Gulf of California, Mexico: northwest 

 of Guaymas, Sonora, 22 fathoms, Albatross (Rathbun, 1892, 1898) ; 

 Arena Bank, 35-40 fathoms, Zaca (Crane). 



Atlantic analogue: Microphrys interruptus Rathbun. 



Diagnosis: Carapace coarsely granulate, anterior branchial regions 

 greatly swollen, spine at lateral angle sharp and slender. Hepatic mar- 

 gins without spines, sometimes with a cluster of granules. Basal antennal 

 article with three spines, the middle one elongate, as are rostral and 

 preorbital spines also. Cheliped of adult male slender, palm not inflated, 

 fingers not widely gaping. Male first pleopod lacking bulbous swelling at 

 base of apex, keel triangular and continuous anteriorly with bluntly 

 pointed tip. 



Description: Carapace triangular. Anterior portion of the branchial 

 region covered by an oblique oblong protuberance, highest on its posterior 

 portion, sloping gradually downward anteriorly and covered with tuber- 

 cles. Gastric region with three tubercles on the median line, a cluster of 



