1917] Nomland: The Etchegoin Pliocene of Middle California 233 



MACOMA INQUINATA AFFINIS, n. var. 

 Plate 9, figures 1, la, lb 

 Type specimen, no. 11092, Univ. Calif. Coll. Invert. Palae. 



Shell large, equivalve, short, trapezoidal, with rather long liga- 

 mental groove. Sides moderately convex, slightly excavated a little 

 below anterior dorsal margin, giving a flange-like appearance, with 

 depressed area on both valves extending from nmbones to posterior 

 dorsal margin. Beaks low, adjacent, a little anterior to middle. 

 Anterior margin evenly rounded, with increased convexity at anterior 

 extremity ; posterior dorsal margin arcuate, with greater curvature 

 behind ligamental groove ; posterior ventral margin concave where 

 intersected by depression extending from beak, on most specimens base 

 more strongly curved a little posterior to middle. Surface covered 

 by numerous, unequal, concentric lines. Dimensions : height, 52 mm. ; 

 length, 64 mm. 



This species may be distinguished from the typical Macoma inqui- 

 nata (Deshayes) by its larger size, the flange immediately anterior to 

 the beaks, depressed area extending from umbones to posterior ventral 

 margin, rather long ligamental groove, and increased convexity near 

 middle of base. 



Occurrence. — Locality 2965, Mya japonica zone, uppermost Etche- 

 goin. 



SEMELE FAUSTA, n. sp. 

 Plate 9, figures 3, 3a, 3b 

 Type specimen no. 11102, Univ. Calif. Coll. Invert. Palae. 



Shell small, inequilateral, with moderately convex valves and low 

 beaks. Posterior end much shorter than anterior ; anterior dorsal 

 margin straight, with evenly rounded anterior end ; posterior dorsal 

 margin slightly convex, with posterior end truncated inwards. Sur- 

 face sculptured by numerous, about equidistant, low, concentric lines ; 

 with a nearly obsolete fold extending from the beaks to the posterior 

 end. Resilifer weak, narrow ; ligamental groove almost obsolete. 

 Right valve with long, rather low laterals ; anterior cardinal indistinct, 

 posterior cardinal low and slender ; left valve with feeble laterals and 

 indistinct, thin cardinals. Dimensions : length, 35 mm. ; height, 30 mm. 



This form is of the same general type as Semele rubropieta Dall, 

 from which it may be distinguished by its having a greater length in 

 proportion to the width, the anterior portion being longer, the fold 



