Order Pterioida Newell 1965
Family Myalinidae Frech 1891
Genus Septimyalina Newell 1942
The bivalve Septimyalina perattenuata has been a rare recovery so far. This single specimen is the only example from both localities. I can observe a columnar prismatic layer on this shell, which is hard to photograph using light.

References
- Newell, N. D., 1942. Late Paleozoic pelecypods: Mytilacea. State Geological Survey of Kansas, Bulletin. 10(2): 1-115. p.p. 64–65

Late Carboniferous Fossils from the Glenshaw Formation in Armstrong County, Pennsylvania
Preface | The Photographic Process
Localities: Locality SL 6445 Brush Creek limestone | Locality SL 6533 Pine Creek limestone
Bivalvia: Allopinna | Parallelodon | Septimyalina
Cephalopoda: Metacoceras | Poterioceras | Pseudorthoceras | Solenochilus
Gastropoda: Amphiscapha | Bellerophon | Cymatospira | Euphemites | Glabrocingulum | Meekospira | Orthonychia | Patellilabia | Pharkidonotus | Retispira | Shansiella | Strobeus | Trepospira | Worthenia
Brachiopoda: Cancrinella | Composita | Isogramma | Linoproductus | Neospirifer | Parajuresania | Pulchratia