ARNOLD — THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 139 



71. Cardium (Trachycardium) quadrigenarium Conrad. 



Cardium quadrigenarium Con., Jour. Phil. Acad. Sci., Vol. VII, 1S37, p. 230, Pi. XVII, fiff. 5; 

 = luteolabrum Gld. (y7(/<r Carpenter, Brit. A.ssn. Rept., 1863, p. 642). Cooper, 7th 

 Ann. Rept. Cal. St. Min., 18S8, page 232. Keep, West Coast Shells, p. 192, 1892. 

 Williamson, Proc. U. S. Nat. Miis., Vol. X\^ 1892, p. 190. Dai.i,, Trans. Wagner 

 Inst. Sci., Vol. Ill, Part. 5, 1900, p. 1091. 



Shell large, oval, ventricose, thick; umbones central, iiromincnt, turned only slightly an- 

 teriorly; surface sculptured with about forty prominent, subangular, smooth, radiating ridges, which 

 are roughened by prominent pointed tubercles on their posterior angle; those ridges near the pos- 

 terior margin are less prominent, but are nodose for nearly their whole length; teeth and interior as 

 in C. corbis: margin sharply serrated. 



Dimensions. — Long. 105 mm.: alt. 105 mm.; diani. 86 mm. 



Di.'itiiignishable hy large size and tiihercuUitetl ridges. Hpecimen^ ideiililied 

 by Dr. Dall. ' 



Found in the upper San Pedro .series of San Pedro, Los Cerrilos and the 

 Long Beach bluff. Found also in the Pleistocene of Twenty-sixth Street and Pacific 

 Beach, San Diego. 



Living. — Monterey to San Diego (Cooper). 



Pleistocene. — San Pedro (Arnold): San Diego (Cooper; Arnold). 



Pliocene. — Calleguas Ranch, Ventura County (Cooper). 



Subgenus Ringicardium Fischer. 



Shell rotund, gaping, with flat ribs and channels, the posterior area with granulose channels; 

 posterior margin sharjily spinose, the spines cros.sing each other ever the ga|); left cardinals when 

 interlocked posterior to the right ones. 



Type, Cardium ringens (Gmel.). 



72. Cardium (Ringicardium) procerum Soimrhy. 



Plate XV. Fig. 6. 



Cardium procerum Sby., Carpenter, Brit. A.ssn. Rept., 1863, p. 620. Dall, Trans. Wagner Inst. 



Sci., Vol. Ill, Part 5, 1900, p. 1091. 

 Cardium panamense , not of Sby., of Cooper, 7th Ann. Rept. Cal St. Min., 188S, p. 232. 



Shell of medium size, suboval, of medium thickness, ventricose, with a rather angular 

 appearance at about one-fourth the length from the anterior margin; surface sculptured by about 22 

 subangular, smooth radiating ridges, with narrow, canel-like grooves between; each valve with 

 three very prominent sharp teeth; margin sharply serrate. 



Dimensions — Long, i mm.; alt. 23 mm.; diam. 19 mm. 



Distinguishable by angular appearance near anterior side, and by the com- 

 paratively small number of smooth radiating ridges. S])ucimens identified by Dr. Dall. 



Rather common in the upper San Pedro .series of San Pedro, Long Beach and 

 Los Cerritos; one specimen from the lower San Pedro series of Deadman Island. Tlie 

 specimen figured is from the upper San Pedro series at San Pedro, and is now in the 



