are widely distributed in the eastern equatorial 

 Pacific. Lampanyctus nobilis is taken at the gyre 

 center and consistently near Hawaii. Its distribu- 

 tion pattern at long. 145°W is thus intermediate 

 between that of the three strictly central water- 

 mass species mentioned above and that of the 

 species which were taken all the way across the 

 transect. Diogenichthys laternatus, G. teniculus, 

 L. omostigma, and A^. resplendens occur over a 

 broad latitudinal range in the eastern equatorial 

 Pacific and in a narrower tongue extending into 

 the central equatorial Pacific (Wisner 1963, foot- 

 note 3; Bekker 1966). None of these species are 

 taken near Hawaii, and only G. teniculus and A^. 

 resplendens are taken near the gyre center, 

 neither very frequently. 



Little is known of the distribution of Diaphus 

 garmani and D. problematicus in the Pacific. 

 Diaphus garmani has been reported from Johnson 

 Island (Nakamura 1970). Wisner (footnote 3) 

 reports it from near Hawaii but it was not taken 

 there by Clarke (1973) nor does it occur at the gyre 

 center. Ahlstrom (1972) recorded D. garmani in 

 "an offshore equatorial belt" but mentions neither 

 species as present in the eastern equatorial Pacific. 

 In the Atlantic, both species occur in equatorial 

 waters, but also occupy a broad latitudinal range 

 in the west (Nafpaktitis 1968). 



Five species were taken principally at lat. 

 3°30'N or the equator. Diaphus signatus and D. sp. 

 (near mollis but apparently distinct from either of 

 the mollis-Uke forms recorded from near Hawaii 

 by Clarke) were taken in abundance at both sta- 

 tions, while D. regani was taken almost 

 exclusively at the equator. A few D. malayanus 

 and Lampanyctus hubbsi were taken at lat. 

 7°30'N, but these species were clearly more com- 

 mon at lat. 3°30'N and the equator. All of these 

 species are found only in the Pacific. There are no 

 reports of any from either the eastern equatorial 

 Pacific or the eastern section of the central water 

 mass. Lampanyctus hubbsi is restricted to the 

 offshore equatorial water mass (Wisner 1963). The 

 same is apparently true of the undescribed species 

 of Diuphus (Wisner footnote 3). The other three 

 species of Diaphus were originally described from 

 farther south or west and near island groups (Gil- 

 bert 1908; Weber 1913; Tuning 1932), and a few 

 were collected in the western Pacific by Kulikova 

 (1961). Wisner (footnote 3) indicates that they oc- 

 cur, like L. hubbsi, in the narrow offshore equa- 

 torial region between ca. long. 130-170°W. 



Diuphus elucens was taken only at lat. 3°30'N, 



and Myctaphum obtusirostrum at lat. 3°30'N and 

 the equator. Their distributions are however, 

 much broader than the present data indicates 

 (Nafpaktitis 1968, 1973). Both are taken consis- 

 tently near Hawaii. It seems likely that their 

 capture only at the above latitudes was due more 

 to their greater abundance there as opposed to 

 their absence from the other latitudes sampled. 

 Centrobranchus choerocephalus was taken only 

 twice (lat. 7°30'N and 3°30'N). Bekker (1966) sug- 

 gests it is a central water-mass species, and it is 

 taken regularly near Hawaii. No real significance 

 can be attached to the capture of only two 

 specimens in the equatorial water mass. 



The remaining species, Myctophum asperum, 

 was taken at all latitudes except lat. 12° N. Its 

 distribution in the Pacific is poorly known. Ahl- 

 strom (1972) records it from lat. 7°N to 2°S between 

 long. 98° and 119°W. It is not taken at the gyre 

 center or near Hawaii. It is apparently, like 

 Diaphus garmani and D. problematicus, neither a 

 central nor eastern equatorial species, but may 

 have a broader distribution to the west. 



Although the data from both the present study 

 and the literature are admittedly fragmentary 

 and we know nearly nothing about distributions 

 south and west of the study area, the evidence 

 indicates that there is no distinct or abrupt 

 change between the shallow-water myctophid 

 faunas of the central and equatorial water masses 

 as defined by Sverdrup et al (1942). While there are 

 at least three abundant central species which did 

 not occur in our equatorial samples, there were 

 more which occurred throughout the sampling 

 area and, in most cases, are also widely distributed 

 in equatorial waters farther east. In between are 

 several central species which occur in the equa- 

 torial water mass to a limited extent-both lati- 

 tudinally (L. nobilis) and longitudinally {Cerato- 

 scopelus warmingi, Diogenichthys atlanticus, and 

 Diaphus frag His ) . 



Within the equatorial water mass, however, 

 there is a distinct and rather abrupt change in 

 fauna. Four species which occur throughout equa- 

 torial waters farther east were taken only at the 

 northern two stations, while five other species 

 which do not occur east of ca. long. 120-130°W were 

 taken at lat. 3°30'N and the equator. There is thus 

 little or no overlap between the ranges of the 

 strictly offshore and those of the eastern equa- 

 torial species whose ranges extend into the study 

 area. 



The change in fauna is close to the northern 



638 



