With the exception of _G. a. microrhyncha_, _G. a. monte_ has the smallest average length of wing of all of the subspecies of _G. alba_. In _G. a. alba_ the length of wing as well as most of the other measurements differ but slightly from those of some of the populations in the Pacific area although the slender bill of the Atlantic bird is a distinctive character, as pointed out by Murphy (1936:1166). TABLE 23. MEASUREMENTS OF SUBSPECIES OF _Gygis alba_ FROM THE ATLANTIC AND INDIAN OCEAN AREA Column headings: A: No. B: Wing C: Longest tail feather D: Shortest tail feather E: Exposed culmen F: Depth culmen G: Tarsus ===================+====+=======+======+=====+=====+=======+========= SUBSPECIES | A | B | C | D | E | F | G -------------------+----+-------+------+-----+-----+-------+--------- _Gygis alba alba_ | 24 | 246 | 99 | 71 | 40 | 8.0 | 14.5 | |239-256|93-111|68-77|35-44|7.5-9.0|13.0-16.5 | | | | | | | _Gygis alba monte_ | 35 | 232 | 106 | 71 | 39 | 8.5 | 13.5 | |224-244|98-116|64-81|37-44|8.0-8.5|12.5-14.0 -------------------+----+-------+------+-----+-----+-------+--------- The taxonomic position of the White Terns of the Pacific area has been one of uncertainty for a long time; as Peters (1934:349) puts it, "It is obvious that the last word on the Pacific races of Gygis has not yet been said." A principal feature of the problem in this region is the presence in the Marquesas of a well-marked subspecies, _G. a. microrhyncha_, virtually surrounded by a wide-ranging and relatively undifferentiated form, _G. a. pacifica_ (Lesson) (see figure 12). The small cormorant (_Phalacrocorax melanoleucus brevicauda_ Mayr) from Rennell Island, Solomons, is another example of a distinct form surrounded by a widely distributed subspecies. In all, 55 adult specimens of _G. a. microrhyncha_ have been examined from the following islands in the Marquesas Group: Mukahiva, Eiau, Motane, Hivaoa, Uapu, Tahuata, Uahuka, Fatuhiva. The measurements are listed in table 24, and show that the White Tern in the Marquesas is a much smaller bird than the other subspecies and has a shorter bill, wing, and tail. The tail possesses a shallow fork as compared with the deeper fork of the tail of other subspecies. In addition, the depth of the culmen averages two millimeters less in the subspecies in the Marquesas. The presence of a wider, black eye-ring is also a distinguishing character in this subspecies.