PLATE LXIX. 
1, 2. Gervillia Lata. ( Broad Gervillia.) Obliquely transverse, inflated; binge-line long, 
oblique ; anterior side short ; posterior side large; beaks obtuse ; surface smooth, with many, 
concentric lines of growth. 
3. Avicula Lanceolata. ( Lanceolate Avicula.) Transversely lengthened, very flat; obliquely 
linear, lanceolate, compressed ; posterior auricle large, obtusely angled ; anterior auricle minute, 
pointed. 
4, 5. G. Acuta. (Acute Gervillia.) Ovate, lanceolate; oblique, narrow, depressed, curved ; shell 
very thin ; anterior part attenuated, opposite extremity rounded. 
6. G. Solenoides. ( Solen-shaped Gervillia.) Transversely elongated; depressed, curved, 
smooth ; anterior end truncated, open ; teeth of hinge irregular, linear. 
7, 8, 9. G. Aviculoides. (Bird's-wing Gervillia.) Obliquely ovate, lanceolate, curved, both 
ends acute; hinge-line nearly one-half length of shell ; teeth few. 
10. Pinna Lanceolata. (Spear-shaped Pinna.) Lanceolate, elongated, arcuated; each valve 
divided into two, flat, sub-triangular parts by mesial line; surface, with longitudinal striae at beaks, 
with transverse, shallow wrinkles. 
11. Perna Quadrata. (Squarish Perna.) Elongated, squarish; valves unequal-sided; gibbose, 
unequal ; hinge-line curved ; beak pointed; surface smooth, with a few, shallow lines of growth. 
12. P. Gracilis. (Slender Pinna.) Elongated, slender, arcuated ; beaks obtuse; anterior side, 
with longitudinal, shallow sulci and remote, shallow, transverse lines of growth. 
13. P. Cuneata. (Wedge-shaped Pinna.) Conical, wedge-shaped; umbones obtuse; surface 
smooth, with a few, transverse, shallow wrinkles. 
14. 15. P. Rostrata. (Beaked Perna.) Ovate, compressed; hinge-line straight, horizontal; 
lesser wing produced, well-defined; base rounded ; beaks obtuse ; shell thin. 
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