20, 2 Dickerson: Review of Philippine Paleontology 203 
Partial list of species from the Vigo group—Continued. 
Terebra javana K. Martin. Dosinia cf. lenticularis. 
Terebra. Dosinia cretacea Philippi. 
Triton pfeifferianum Reeve. Glycimeris viteus (Lamarck). 
Trochus. Glycimeris angulatus (Lamarck). 
Telescopium telescopium Lin- Ostrea. 
nus. Paphia textrix Deshayes. 
Trivia smithi K. Martin. Pecten (Pleuronectia) pleuro- 
Voluta cf. innexa Reeve. necta Linnzus. 
PELECYPODA Pecten cf. radula Linnzus. 
sin ibvaa tases. Pecten cf. pseudolima Sowerby. 
Arca ferruginea Reeve. Pecten pseudolima Sowerby. 
Arca granosa Linneus. Pecten cf. cristularis Adams and 
Arca cf. coelata Reeve. Reeve. 
Arca tenebrica Reeve. Placuna placenta Linnzus. 
Barbatia fusca (Bruguiere). Psammobia cf. lessoni Blainville. 
Cardium. Psammobia sp. 
Cardium attenuatum Sowerby. Pinna sp. 
Cardium donaciformis Cuming. Solen sp. 
Cardium unicolor Sowerby. Spisula sp. 
Cardita antiquata Linnzus. 
Chione chlorotica Philippi. Solecurtus quoyt Deshayes 
Chione? Spondylus sp. 
Corbula scaphoides Hinds. Tellina, Sp. 
Corbula socialis K. Martin. Tellina sp. 
Clementia hyalina Philippi = C. Vermetus javanus? K. Martin. 
papyracea. Vermetus sp. nov. 
In the above list about 75 per cent of the specifically deter- 
mined forms are living species, an astonishing percentage when 
the geologic history of the region yielding these forms is consid- 
ered. The extinct forms are practically all common to the 
upper Miocene of Java according to K. Martin, * and they are > 
practically all highly organized species. Such highly developed 
species are particularly fitted to their surroundings, and a slight 
change in life conditions might cause the extinction of the spe- 
cies or bring about a specific change.** As was noted above, the 
- percentage of Recent species is remarkably high, and it is the 
writer’s conclusion from a detailed study of the subject that the 
evolution of marine molluscan faunas in the Tropics is far slower 
than in the Temperate Zones. On this account the same “vard- 
stick” in the Tertiary geological time scale cannot be applied in 
both tropical and temperate regions. The scale used in the Tem- 
perate Zones is approximately as follows: Eocene, 0 per cent 
living species but practically all genera living; Oligocene, 3 per 
"Martin, K., Tertidrschichten auf Java. Leiden (1880) 44-51. _ 
_ “Dickerson, R. E., Philip. Journ. Sci. 18 (1921) 1-23. This subject 
1s discussed in detail in the paper cited. 
