16 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Stenocionops contigua (Rathbun), a synonym of S. angusta (Locking- 

 ton) ; Eupleurodon peruvianus Rathbun (1924a), a synonym of Epial- 

 tus peruvianus Rathbun (1923a), which, when transferred to Eupleuro- 

 don, becomes Eupleurodon peruvianus (Rathbun, 1923a) ; Mithrax 

 (Mithrax) sonorensis Rathbun, a synonym of Herbstia camptacantha 

 (Stimpson) ; Epialtus crenulatus Rathbun, a synonym of E. minimus 

 Lockington ; Mithrax (Mithrax) orcutti Rathbun, a synonym of M. 

 (M.) armatus Saussure; Podochela barbarensis Rathbun, a synonym of 

 P. lobifrons Rathbun. 



Species adequately illustrated for the first time are Podochela angu- 

 lata Finnegan, Eupleurodon trifurcatus Stimpson, and Herbstia pubes- 

 cens Stimpson. Figured for the first time are male first pleopods of all 

 Pacific American genera and of most Pacific American species of Majidae, 

 and first and second pleopods of all Pacific American genera and species 

 of Parthenopidae and Hymenosomidae, the only previous figures being 

 those of Eurypodius latreillei by Brocchi (1875), of Oregonia gracilis 

 by Shen (1932), and of Pitho species by Rathbun (1925). 



Territory Covered 



The Pacific coast of North and South America, from Bering Strait 

 to the Strait of Magellan, together with outlying island groups, consti- 

 tutes the geographical area under consideration. However, since several 

 of the boreal species treated occur on the Asiatic coast as well, and since 

 several of the austral species occur also on the Atlantic coast of South 

 America, citations to the extralimital occurrences of such Pacific species 

 have been included in the appropriate synonymies. 



In the case of tropical species that occur also in the Atlantic, this 

 has not been done for two reasons: first, because, with the increasing 

 refinement of systematic investigation, such species are becoming con- 

 stantly fewer in number; and second, because such references more ap- 

 propriately belong in a contemplated separate report on the collections 

 of the Velero HI in the Caribbean in 1939. Studies on the Atlantic 

 Majidae have proceeded concurrently with those on the Pacific and a 

 consistent method of treatment will be applied to both segments of the 

 family. The few Atlantic genera not represented in the Pacific have been 

 included in the keys here presented with a view toward obviating the 

 necessity of their subsequent repetition. 



