ACADEMY OF NATURAL SCIENCES. 13 



Description of two New Species of Bivalve Shells, from the 

 Tertiaries of Contra Costa County. 



BY AUGUSTE REM0ND. 



Cardium Brug. 

 C. Gabbii Remond. 



Shell cordate, ventricose, nearly equilateral ; posterior side truncated, direct ; 

 anterior side slightly depressed ; height and length nearly equal. Umbones very 

 prominent ; beaks incurved, approximate ; lunule well marked, carinated ; sur- 

 face even, with fine imbricated lines of growth. Hinge (of the left valve) com- 

 paratively narrow ; anterior fosset small, shallow, triangular ; cartilage pit 

 large, deep, long ; lateral teeth heavy, thick, prominent. 



Locality : vicinity of Kirker's Pass, south of New York (of the Pacific) Plain 

 from a late tertiary deposit. 



The C. Gabbii will easily be distinguished from any other species yet discov- 

 ered, from its heavy hinge and enormous lateral teeth. I take great pleasure in 

 dedicating this beautiful fossil to Mr. W. M. Gabb, to whom I am indebted for 

 repeated assistance in my palsontological studies. 



This species occurs in shelly sands, together with Tapes regitlaris Gabb and 

 Murex ponderosus Gabb, two other extinct species. The specimens are in the 

 collection of Mr. W. M. Gabb and my own. 



Ostrea L. 

 O. Bourgeoisii Rernond. 



The description is from two lower valves, from the collections of Mr. l'Abbe 

 Bourgeois (Pont-Levoy, France) and Mr. Pioche, (San Francisco.) 



Shell sub-oval, higher than long, strongly contracted near the cardinal area, 

 sub-rounded on the ventral margin ; inferior valve comparatively thin, convex, 

 irregular exteriorly, with remote, somewhat rugose, plaits of growth. Liga- 

 ment fosset long, profound, minutely wrinkled and finely striated, oblique and 

 turned downwards ; muscular impression very large, oblique, and sub-central, 

 somewhat prominent. 



Locality : vicinity of Kirker's Pass, from a late tertiary bed. 



1 dedicate this new species to Mr. Bourgeois, Professor of Natural History 

 at the School of Pont-Levoy, (Loir-et-Cher, France) who was my first teacher 

 in geology. 



Description of two Species of Scutella. 



BY AUGUSTE REMOND. 



Scutella Lam. 



S. Gibbsii Remond. 



Disk oblong-sub-oval, rounded before and truncated behind, posteriorly cob- 



vex above, slightly depressed in front ; inferior surface flat, somewhat concave 



about the mouth. Apex about midway between the center and posterior mar- 



