We have no definite information as to the systematic position of the genus
Macclintockia; some species of the genus has usually been recognised as a representative of the Urticaceae or Myrtaceae on. the ground of similarity in the leaves but one of the species,
M. lyallii from Kôbe, has great similarity to the leaves of
Putamogetun franchetii, one of the species of Potamogetonaceae.
From the geological occurrences it appears that the genus was widely distributed from the Cretaceous to the Miocene, but it was absent in East Asia in the upper Miocene age. The specimens, which were stored in the Institute of Geology and Palaeontology of the Telhoku Imperial University, Sendai, are as follows: I.
Macclintockia trinerris HEER.
Localities: 1. Tei, Maoka-mati, Karafuto.(Nisisyakutan formation)(Figure 1.)
2. Honbetu, Mikasayama-mura, Sorati-gun, Hokkaidô.(Poronai Series)
3. Horonitatibetu, Numata-mura, Uryu-gun, Hokkaidô, (Poronai Series)(Fugure 2.)
4. Yubari-mati, Yubari-gun, Hokkaidô.(Poronai Series)
5. Otiai-ike, Suma-ku, Kt-pe, Honsyû.
II.
Macclintockia cfr. trinervis HEER.
Locality: Konsyun, Manchoukuo.
III.
Macclintockia lyallii HEER. Locality: Okuhata, Suma-ku, Kobe, Honsyû.
IV.
Macclintockia sachalinensis KRYSFITOFOVICH Locality: Tymovskaya Padj near Niklewicz's coal mine, North Saghalin.
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