TERTIARY FOSSILS. 53 



from Japan, and have no reason to doubt but that the specimen came from Japan 

 with the collection. Mr. Tryon has long held the belief that it was mixed with 

 the others by accident, and that it was a California specimen. However that may 

 be, I cannot tell; and we have, at present, no means of settling the question. The 

 species is found in California in both a recent and fossil state, large valves being 

 quite common in the Post-Pliocene of San Pedro ; nevertheless I do not consider 

 this any proof that it may not, likewise, be found living in Japan. 



The individual figured is quite young, and is recent. It was kindly given to me 

 by Mr. R. E. C. Stearns of San Francisco. 



SILIQUARIA, Solium. 



? S. EDENTULA, D. 8. 

 PI. 15, Fig. 11. 



Shell moderately large, thin, flattened, elongated sub-elliptical, 

 nearly equilateral ; beaks minute, a little posterior to the middle, 

 projecting almost insensibly beyond the cardinal line; cardinal 

 margin sloping slightly and perfectly straight towards the two 

 ends; anterior end convexlyand very obliquely subtruncate above, 

 produced and rounded below; posterior end broadly and regu- 

 larly rounded, a little less prominent below than above the middle; 

 basal margin nearly straight. Surface nearly smooth in the mid- 

 dle, marked by pretty distinct lines of growth towards the ends, 

 especially above. 



Length from beak to base, 1.3 inch ; width, 2.6 inch ; beak to anterior end, 1.45 

 inch. From the Pliocene of San Fernando. 



On exposing the hinge of this shell, I was unable to get at the characters in a 

 perfectly satisfactory manner, owing to its extreme thinness and delicacy. The 

 teeth, if they exist, are very small, and seem to be almost entirely obsolete. It is 

 possible that further examination will develop some characters of the hinge which 

 will remove it entirely from the above genus, but I preferred placing it here pro- 

 visionally, where it seems most nearly related, to proposing a new generic name 

 on insufficient grounds. 



