1917] Nomland: The Etchegoin Pliocene of Middle California 231 



DESCRIPTION OF SPECIES 

 ANODONTA NITIDA, n. sp. 

 Plate 9, figure 2 

 Type specimen no. 11091, Univ. Calif. Coll. Invert. Palae. 



Shell of moderate size, equivalve, thin, rather compressed, ventral 

 part of sides of posterior end flattened, with subpentagonal, angular 

 outline. Beaks low, inconspicuous. Anterior region about one-fourth 

 of length of shell ; anterior dorsal margin rounded, with slightly in- 

 creased convexity a short distance in front of beaks ; anterior extremity 

 rather sharply angular ; posterior extremity slightly truncated ; pos- 

 terior dorsal margin to upper angle of truncation nearly two-thirds 

 of distance from beak to posterior end ; from this angle to lower angle 

 of truncation margin is slightly concave ; posterior ventral margin has 

 increased convexity slightly more than one-third of length of shell 

 from posterior end. Surface ornamented by numerous wide concentric 

 ridges. Height, 38 mm. ; length, 54 mm. 



This species may be recognized by compressed form, inconspicuous 

 anteriorly located beaks, angular outline, and flattened posterior ven- 

 tral portion of sides. 



Occurrence. — At locality 2999, on ridge a little east of middle of 

 southern boundary of sec. 12, T. 22 S, R, 17 E, M. D. B. & M., northern 

 end of Kettleman Hills. At the type locality this species occurs with 

 Goniobasis, sp., in fresh-water horizon at or near the base of the upper 

 Etchegoin. 



PECTEN EGEEGIUS, n. sp. 

 Plate 6, figures 3, 3a, 3b 

 Type specimen no. 11090, Univ. Calif. Coll. Invert. Palae. 

 Shell equilateral, equivalve, thin, rather compressed ; with smooth, 

 regularly rounded base. Dorsal margins long; umbonal angle about 

 70 degrees. Right valve with about 22-23 moderately strong, rounded 

 ribs; in each interspace there is one small, often invisible, rounded 

 riblet; anterior ear long, arcuate in front, ornamented above byssal 

 notch by about six distinct, radiating ridges and numerous incremental 

 lines; byssal notch well defined; posterior ear very small, sculptured 

 by low radiating ridges and inconspicuous incremental lines. Left 

 valve with about 22 subequal ribs, which are not so prominent as those 

 of the right valve, but with auxiliary riblets more distinct ; anterior 

 ear large, with sculpture consisting of faint incremental lines and 

 about twelve radiating ridges; posterior ear similar to that on the 



