The third quarter issues supposedly cover the stamps issued from July to September but the Philippine Postal Corporation (Philpost) did not release any stamps for the month of September. Featured here are the complete listings of the stamps.
The Yuchengco Group of Companies (YGC) celebrated their centennial with a stamp released on July 20, 2011 with the design featuring the old and new YGC complex and their centennial logo.
After the release of the EDSA @ 25 pre-stamped envelopes some months earlier, Philpost finally came up with stamps to highlight the said event. The EDSA People Power Revolution 25th Anniversary stamps were issued on August 1, 2011. The 7p se-tenant block of 4 stamps highlight former president Corazon Aquino and Manila Archbishop Jaime Cardinal Sin. A 56p souvenir sheet completes the set.
On August 15, 2011, a se-tenant block of 4 stamps were issued to highlight the 60th anniversary of Holy Cross of Davao College Inc. The designs featured the Bajada Campus Facade, Grade School and High School Buildings, Palma Gil and Mabutas Halls, and lastly, the Babak and Camudmud Campuses.
Two days later, a new set of definitives featuring the Philippine Marine Biodiversity series was released by Philpost. The August 17, 2011 stamps showcased the 1p Dendronepthya Soft Coral, 5p Sea Apple, 7p Spotted Boxfish, and the 9p Broadclub Cuttlefish.
The 300th Death Anniversary of Mother Francisca del Espiritu Santo de Fuentes was celebrated on a 7p stamp that came out on August 24, 2011. The nun and her various works were highlighted on the stamps.
The last stamp for the quarter showcased the Philippine Endemic Lizards. The 7p se-tenant block of 4 stamps feature the Luzon Giant Forest Skink, Luzon Karst Gecko, Southern Philippine Bent-toed Gecko and Luzon White-Spotted Forest Skink. The 28p souvenir sheet featured the Philippine Forest Dragon, Philippine Spring Stream Skink, Philippine Sailfin Lizard and Cordilleras Slender Skink. A miniature sheet of 16 valued at 112p is also available,