Clark: The San Lorenzo Series of Middle California 123 



Family Ledidae 

 Genus LEDA Schumacher 

 LEDA ELONGOROSTRATA, n. sp. 

 Plate 13, figure 16 

 Type specimen 11206, Coll. Invert. Palae. Univ. Calif., loc. 2755 

 Shell small, thin, elongate-ovate, narrow and abruptly attenuated. Anterior 

 end rather narrow but regularly rounded; beaks inconspicuous, anterior to the 

 middle; posterior dorsal margin long, straight, only sloping very slightly; anterior 

 dorsal edge gently convex; ventral edge long and gently arcuate. Lunule and 

 escutcheon both elongate-lanceolate. Surface covered by fine concentric, somewhat 

 irregularly spaced lines of growth. On the rostrate end a shallow, rather broad 

 sulcus extends from the beak to the lower side of the posterior end. Internal 

 character of shell unknown. 



Dimensions. — Length, about 18 mm.; height, 7 mm. 



Occurrence. — Type specimen from University of California locality 2755; also 

 found at localities 205, 1165 and 1312. 



LEDA MARKLEYENSIS, n. sp. 

 Plate 14, figure 7 

 Type specimen 11272, Coll. Invert. Palae. Univ. Calif., loc. 3081 

 Shell small, acutely rostrate posteriorly ; beaks opisthogyrous, anterior to 

 middle ; posterior dorsal margin strongly concave, longer than anterior dorsal 

 margin, which is gently convex; posterior end sharply pointed; anterior end 

 regularly rounded. Surface covered by medium-fine, regular incremental lines ; 

 escuteheonal area flat, fairly broad, depressed nearly at right angles to the main 

 outer surface of shell. Lunule and hinge plate not exposed. 



Dimensions. — Type specimen: length, 16 mm.; length from posterior end to 

 medium line, 10 mm. ; height, about 7 mm. 



Occurrence. — On the west side of Markley Canon, north of Mount Diablo, at 

 University of California locality 3081. 



Leda marldeyensis resembles Leda gabbi Conrad 02 in outline, from 

 which it differs in being somewhat higher in proportion to the length ; 

 the beaks are more anterior, and the escuteheonal area is different. 



LEDA PULCHRISINUOSA, n. sp. 

 Plate 11, figures 5 and 6 

 Type specimen 11109, Coll. Invert, Palae. Univ. Calif., loc. 1131 

 Shell small, subovate ; beaks near the middle. Dorsal slopes nearly equal, the 

 posterior one, which is slightly the longer, being gently concave ; anterior slope 

 nearly straight. Anterior end regularly rounded; posterior end acutely rostrate. 

 Lunule narrow, elongate-lanceolate, extending a little over half the length of 

 the anterior dorsal edge. Escutcheon well defined, strongly depressed, lanceolate, 



92 For original description of Leda gabbi, see L. protexta, Geol. Surv. Calif., 

 Palaeontology, vol. 1, p. 199, pi. 26, fig. 185 ; listed at first by Gabb as Leda 

 protexta, renamed by Conrad. L. protexta is an East Coast species. 



