Four species of apogonid ®shes are described as new from the Marquesas Islands. Apogon lativittatus, similar to A. semiornatus, differs in having 13 instead of 12 pectoral rays, 4.5±5.5 scales above the lateral line, 19±23 circumpeduncular scales, a straighter dorsal pro®le of the head, deeper body on the average, opaque red color as an adult with the same midlateral blackish stripe posteriorly on the body and caudal ®n, but the oblique dark band on head reduced, and in larger size (to 58.4 mm SL); the type specimens include one from the Line Islands (A. semiornatus remains unknown from islands of Oceania). Apogon relativus, with ®ve dark stripes and pink ®ns, is similar to A. angustatus, differing in having narrower stripes, a larger and vertically elongate black spot at midbase of caudal ®n in adults, and a broader interorbital space (bony width 4.05±4.8 in head, compared with 5.0±5.95 for A. angustatus). Apogon sinus, collected in very shallow water at the head of deep bays, is uniquely colored with seven narrow dark stripes on the body, but none on the lower third of body anterior to the caudal peduncle; it is most similar to the wide-ranging allopatric A. taeniophorus, from which it differs in a deeper body (2.6±2.9 in SL, compared with 2.8±3.2), broader interorbital space (4.2±4.45 in head, compared with 4.5± 5.35), and in having 16±17 instead of 17±19 gill rakers. Pseudamiops phasma is described from two specimens. Like the three other species of the genus, it is elongate and compressed, with deciduous cycloid scales, no lateral line, ventral spine posteriorly on the maxilla, and largely transparent body; it differs variously from the others, but from all in having 19 compared with 14±18 pectoral rays. The ®sh fauna of the Marquesas Islands in the South Paci®c, the northernmost archipelago of French Polynesia, is relatively impoverished. Only 415 species of shore ®shes are known from these islands (Randall and Earle in press), compared with 633 for the Society Islands (Randall 1985, revised by Myers 1999). Although there has probably been more ®sh collecting in the Societies, it is very evident that there are fewer ®shes in the Marquesas when one compares the number of species in families of which the species are readily observed and collected. For example, the Society Islands has 27 chaetodontids, 11 pomacanthids, 33 pomacentrids, 50 labrids, and 19 scarids. The respective numbers for these families in the Marquesas are 15, 3, 21, 33, and 6. The Marquesas are also special in having the third highest level of endemism of shore ®shes in the Paci®c, 11.6% (Randall and Earle in press), after Hawai`i with 23.1% and Easter Island with 22.2% (Randall 1998). The basis for the high endemism of the Marquesas appears to be their isolation and variable sea temperature. The Marquesas lie between latitude 7 50 0 S and 10 35 0 S and longitude 138 25 0 W and 140 50 0 W. They are high islands of volcanic origin that rise steeply from the sea bottom at depths greater than 4000 m. There are no barrier reefs, hence no lagoons, and relatively little live coral. The sea-surface temperature for the region from 1982 to 1998 averaged 27.5 C, with extremes 47 1 Manuscript accepted 2 March 2000. 2 Bishop Museum, 1525 Bernice Street, Honolulu,