16 The Philippine Journal of Science 1921 
In Japan it is found not only in Lepidocyclina and Miogysina-limestone 
and similar and equivalent beds of Formosa, Botel-tobakee, the Riukiu 
Islands and the Ogasawara-Jima, but also in the Lepidocyclina and Mio- 
gysina-limestones of the provinces of Sagami and Kae, 2, the Lithotham- 
nion-limestones of Oyami-Yama and Megami-yami near Sagau, Province of 
Lotomi; and 3, the Lithothamnion-limestone intercalcated in an oil-bearing 
Tertiary complex of Echigo, 4, the Lithothamnion-limestone of Shiroiwa, 
Makatsuka-mura, Otsu-gou, Province of Natigo. 
It is evident from these references that this form has con- 
siderable range in the Miocene and probably the Pliocene. 
From all the evidence Canguinsa and Upper Vigo beds may 
be assigned to some stage of the Miocene, and the evidence of 
Lepidocyclina indicates a still greater age, the Oligocene. 
IMPORTANCE OF GUIDE FOSSILS 
Good guide fossils are far more difficult to select in connection 
with tropical Tertiary faunas of the Philippines than in con- 
nection with the California Tertiary, owing to the great pre- 
dominance of Recent mollusca. As will be seen from a study of 
the fauna cited above, most of the forms which are extinct were 
originally described from a correlative horizon in Java. Of 
these, the writer is inclined to think that Cerithium jenkinsi, C. 
herklotsi, C. bandongensis, Mitra javana, M. jenkinsi, M. jung- 
huhni, M. hucciniformis, Turris coronifer, Terebra bicincta, 
Terebra javana, Vicarya callosa, and Vermetus javanus will prob- 
ably prove reliable guides among the mollusca. All of these 
species are representatives of highly organized genera and their 
extinction during the post-Miocene time was probably due to 
their inability to obtain life conditions suited to their highly 
specialized needs. 
Corals, echinoderms, and the more highly organized forami- 
nifera will probably prove to be even better horizon determiners, 
but their comparative infrequence in strata of the Philippines 
will at times preclude their use. The writer has not yet at- 
tempted to identify the corals and the echinoderms in the collec- 
tions made, but their value will no doubt prove to be great. It 
seems that their evolution may have been greatly retarded, but 
much study will be required in this connection. For strati- 
graphic work in the Tropics, large and complete collections are 
necessary to obtain results of any value as, even with the best 
data available, geologic and paleontologic history is read with 
much difficulty. Much comparative material, both Recent and 
fossil, should be accumulated, as subspecific differences will be 
