406b Thirty-fifth Report on the State Museum. 



Crenipecten, Hall. Like Pecten or Aviculopecten in form. Hinge 

 furnished with a series of small cartilage pits throughout its entire 

 length. 



Examples — Crenipecten Winchelli. PI. i, figs. 4, 5. 

 Crenipecten Leon. PI. i, fig. 6 . 

 Crenipecten amplus. PI. i, fig. 7. 

 Crenipecten crenulatus. PL i, figs. 8, 9. 



Aviculopecten, McCoy, is emended to include those forms which have 

 the hinge-line usually shorter than the transverse diameter, and both 

 ears well-defined. Test ornamented with rays. 



Examples — Aviculopecten princeps. PI. ii, figs. 1-4. 

 Aviculopecten fasciculatus. PI. ii, fig. 5. 

 Aviculopecten duplicates. PL ii, fig. 6. 

 Aviculopecten rugcestriatus. PL ii, fig, 7. 

 Aviculopecten dolabriformis. PL ii, fig. 8. 

 Aviculopecten insignis. Pl.'ii, fig. 9. 

 Aviculopecten bellus. PL ii, figs. 10, 11. 



Lyriopecten, Hall. Differs from the preceding in the short hinge- 

 line and very small anterior ear. Test usually ornamented with strong 

 rays. 

 Examples — Lyriopecten magnificus. PL ii, fig. 12. 



Lyriopecten interradiatm. PL ii, fig. 13. 

 Lyriopecten cymoalon. PL ii, fig. 14. 



Pterinopecten, Hall. Hinge-line long. Ears not well-defined, being 

 simple expansions or extensions of the upper lateral margins to the 

 hinge-line. Test ornamented with rays. 

 Examples — Pterinopecten undosus. PL i, figs. 12, 13. 

 Pterinopecten vertumnus. PL i, figs. 14, 15. 

 Pterinopecten erectus. PL i, fig. 16. 



Pterinea, Goldfuss. Shell inequi valve, inequilateral ; posterior side 

 alate; anterior end nasute or auriculate. Ligament internal; liga- 

 mental area longitudinally striated. Cardinal teeth two or more. 

 Lateral teeth linear oblique. Posterior muscular impression large, 

 situated on the post umbonal slope. Anterior muscular impression 

 small, situated within the rostral cavity. Test ornamented with rays. 



Examples — Pterinea fldbella. PL iii, figs. 1-3. 



Pterinea Chemungensis. PL iii, fig. 4. 



S. g. Vertumnia, Hall. Differs from Pterinea in -having the right 

 valve convex, and the left flat or concave. Hinge area narrow. 



Example — Pterinea ( Vertumnia) reversa. Page 294. 



Actinopteria, Hall. Differs from Pterinea in the absence of a 

 broad striated ligamental area and strong cardinal and lateral teeth. 

 Right valve subconvex. Surface with fine rays. 



Examples — Actinopteria subdecussata. PL iii, fig. 9. 

 Actinopteria Boydi. PL iii, figs. 10, 11. 

 Actinopteria eta. PL iii, figs. 12, 13. 

 Actinopteria muricata. PI . iii, fig. 14. 



