276 The Philippine Journal of Science 1913 



their splendid ornamentation and striking colors. The oldest 

 fossil species are small, thin shelled, and have little ornamenta- 

 tion. (Zittel.) 



Spondylus sp. Plate VIII, fig. 7. 



The form here shown is only an internal cast, and therefore 

 I am unable to place it specifically. It is marked by 4 very 

 strong and prominent ribs which extend downward into spines. 



Locality: Unknown. 



Formation : Limestone. 



Spondylus ducalis Chem. ( ?) Plate X, figs. 3 and 4. 

 Mus. Bolten (2), 1798, 194. 



This and the above are two specimens which belonged to the 

 Spanish Mining Bureau, the labels of which were lost so that we 

 know nothing definite about the locality or the horizon from 

 which they came, except that they came from a limestone 

 formation. 



Spondylus ducalis is still living in Philippine waters on the 

 coasts of Luzon, Cebu, and Mindanao. 



The fossil shown here is flatter than S. ducalis and more worn. 

 The flatness of the smaller valve may be due to compression or 

 may be natural. 



PlilCATTJLA Lamarck 



Shell irregular, flat or considerably arched with the beak 

 of the right valve attached; smooth or wrinkled; hinge area 

 indistinguishable, the ligament internal between two or more 

 diverging ridge-like hinge teeth ; the muscle simple and excentric. 

 Numerous fossil species from the Trias on, as well as about 

 10 living. (Zittel) 



Plicatula imbricata Menke. Plate X, fig. 6. 

 Sowerby, Plicatula 6 and 15-18. 



Cuming collected this species on the beach of Corregidor Island 

 at the entrance to Manila Bay. 



Locality : Sea cliff near Puerto Princesa, Palawan, No. 779. 



Formation: Recently elevated limestone. 



LUCINIDiE 

 LTJCINA Bruguiere 



Shell more or less circular or lens shaped, compressed or bulg- 

 ing; the posterior side often has a furrow extending from the 

 back to the posterior margin ; lunule generally present ; ligament 

 exterior, frequently deeply sunken; hinge variable, generally 



