_Characters._--Adult: Resembles _M. l. senex_, but crown slightly darker gray; back, wing-coverts and scapulars more heavily washed with olivaceous-brown; mantle less slate; underparts paler and more brownish, especially belly. (Note--The specimens examined from the Marianas are old and rather worn in appearance.) _Measurements._--Two males measure: wing 180?, 182?; tail 62, 63; tarsus 55, 55; three females: wing 181?, 181?; tail 55, 59, 62; tarsus 54, 54, 56. Takatsukasa (1932: 10) lists the following measurements: males--wing, 155-169; tail, 54-62; culmen, 22.5-24; tarsus, 51-54; females--wing, 158-170; tail, 56-65; culmen, 23-25; tarsus, 50-55. _Specimens examined._--Total number, 10 (3 males, 4 females, 3 unsexed), as follows: Mariana Islands, AMNH--Guam, 1 (June 6)--Saipan, 6 (1895)--Asuncion, 3 (1904). _Nesting._--Concerning the nest of the Micronesian Megapode in the Marianas, Takatsukasa (1932:10) writes: "The nest is a large mound of sand mixed with grass and is made in the wooded land along the seashore. The mound is over one hundred feet in circumference and a few yards in height, and is built by the united efforts of the male and female, by scratching sand and grass with their large feet. The eggs are laid in this mound and they are hatched by the heat of the sun and that produced by the fermentation of the grass, and they are never hatched by the parent birds. The egg is of a pale brown, but always stained by nesting materials." Takatsukasa (1932:11) quotes Oustalet as follows: "Specimens collected by Mr. Marche have proved that the breeding season of La Pérouse's Megapode is rather long, like the other species of the same family, it begins to breed in January or February and ends in June. Accordingly, in this period the eggs just laid, the chicks, the young and adult can be seen at one place, but Mr. Marche did not obtain any egg." Hartert (1898:61) records a chick taken on July 17. Yamashina (1932a: 411) records eggs taken in 1931 as follows: two eggs from Pagan, February 17; three eggs from Pagan, May 15; four eggs from Agrihan, June 24. The breeding season for both of the incubator birds, _M. l. senex_ and _M. l. lapérouse_, is apparently from about January to August.