124 PALAEONTOLOGY OF CALIFORNIA. 



so as to unite with the posterior canal. Surface marked by 

 prominent longitudinal ribs, crossed by distinct revolving linear 

 ribs, very uniform in size, and with interspaces of about the same 

 size as the ribs. 



Figure, slightly magnified. 



Localities: Martinez, and near Fort Tejon. 



In 1861, in my "Synopsis of the Mollusca of the Cretaceous Formation," I 

 used Klein's name, in preference to that of Lamarck's, for this genus. Since 

 then, in common with the majority of American conchologists and palaeontolo- 

 gists, I have determined to ignore all pre-Linnsean names, unless first adopted 

 under the binomial system by some subsequent author, on account of the con- 

 fusion which must inevitably arise, unless we have some settled starting-point 

 for our nomenclature. 



R. (RlMELLA) SIMPLEX, 11. S. 

 PI. 20, Fig. 80. 



Shell elongated, robust ; spire high ; whorls about seven, 

 rounded ; suture distinct. Surface marked by numerous longi- 

 tudinal ribs, small on the upper volutions, becoming larger, 

 more distant, oblique, and proportionally shorter, as the shell 

 increases in size ; these are crossed by small, regular, revolving 

 lines. Outer lip suddenly expanded ; posterior canal continued 

 along the surface of the penultimate whorl; anterior canal sud- 

 denly recurved. Aperture unknown. 



Figure, natural size. 



Locality: Collected by Dr. Cooper, at San Diego; and I have found a single 

 specimen at Clayton, in the strata above the coal (Division B.). 



Larger than the preceding species, and easily distinguished by its large, longi- 

 tudinal ribs. 



PUGNELLUS, Con. 



P. HAMULUS, n. S. 



PI. 20, Fig. 81, and PI. 18, Fig. 48. 



Shell robust; spire moderately high; whorls six, angular, 

 sloping above and crenulated on the carina. In the immature 



