150 
PACIFIC SCIENCE, Vol. XII, April, 1958 
evolved in and dominated the northeastern 
Atlantic phoxocephalid fauna. In light of the 
cold water habitats of the species of the gen- 
era in question, the migration pathway for 
these events undoubtedly occurred north of 
the American or Asian continents. 
In the western Atlantic Ocean, along the 
warmer eastern shores of the Americas, is a 
Paraphoxus fauna closely allied and in some 
cases identical specifically with that in the 
tropical and semitropical eastern Pacific 
Ocean. It is of considerable interest that none 
of these paraphoxids has appeared in the 
warmer eastern Atlantic, suggesting difficulty 
or slowness of migration, or the inability to 
compete in the harpiniid-dominated eastern 
Atlantic. 
Although these facts are meager they never- 
theless point to a pressure of migration from 
the generalized and mixed phoxocephalid 
faunas of the northeastern Pacific Ocean to 
the more specialized, sparser, and geograph- 
ically isolated faunas of the Atlantic Ocean. 
It is advisable to retain the name Harpiniop- 
sis for a group of species which are closely 
related to a theoretical precursor of the genus 
Harpinia and which, through distributional 
studies, may shed further light on the rela- 
tionships of Pacific and Atlantic faunas. 
KEY TO THE EXISTING GENERA OF 
PHOXOCEPHALIDAE 3 
1. Peraeopod 3, article 2 more than twice as 
wide as article 3 2 
1. Peraeopod 3, article 2 about as wide as 
article 3 6 
2. Maxilla 1, palp biarticulate 3 
2. Maxilla 1, palp uniarticulate 4 
3. Antenna 2, flagellum multiarticulate, gna- 
thopods 1, 2 similar in size. Paraphoxus 
3. Antenna 2, flagellum biarticulate, gnatho- 
pod 1 much larger than 2. . .Joubinella 
3 The genus Phoxocephalopsis Schellenberg, 1931, was 
placed in the family Haustoriidae by K. H. Barnard, 
1932, although it is intermediate between that family 
and the Phoxocephalidae. 
4. Mandible, molar bearing ridges and cusps 
Phoxocephalus 
4. Mandible, molar smooth or with a few 
spines 5 
5. Eyes present, maxillipedal palp article 3 
unproduced Metaphoxus 
5. Eyes absent, maxillipedal palp article 3 
produced conically . Leptophoxus 
6. Eyes absent 7 
6. Eyes present 9 
7. Head with dorsal crest, uropod 2 with 
apical ramal spines Pseudharpinia 
7. Head lacks dorsal crest, uropod 2 lacks 
apical ramal spines 8 
8. Antenna 2 in male very short 
Harpinia 
8. Antenna 2 in male as long as body 
Harpiniopsis 
9. Antenna 2 with basal ensiform process. . 
Heterophoxus 
9. Antenna 2 lacks basal ensiform process. . 
Proharpinia 
REFERENCES 
Alderman, A. L. 1936. Some new and little 
known amphipods of California. Calif. 
Univ. Pubs., Zool. 41(7): 53-74, 51 figs. 
Barnard, J. L. 1955. A list of phoxocephalid 
Amphipoda identified from samples of the 
benthos of San Pedro Basin, California. 
IN O. Hartman, Quantitative survey of 
the benthos of San Pedro Basin, Southern 
California. Part I. Preliminary results. Han- 
cock Pacific Exped. 19(1): App. C, pp. 1 59— 
163. 
Barnard, K. H. 1930. Amphipoda. Brit. 
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Hist. Rpts., Zool. 8: 307-454, 63 figs. 
— 1932. Amphipoda. Discovery Rpts. 5: 
1-326, 1 pi., 174 figs. 
Chilton, C. 1909- The Crustacea of the sub- 
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Gurjanova, E. 1938. Amphipoda, Gam- 
maroidea of Siaukhu Bay and Sudzukhe 
