MEXICAN BOUNDAEY LINE. 151 



intervals of the larger ribs, which latter have on each side a raised line or fine rib, giving it a 

 trifid character ; upper valve suhconcave. 



This species differs from P. quadricostatus, Sowerby, in having but two equal ribs between 

 the larger, while that species his three corresponding ribs, and it is also proportionally a nar- 

 rower or more elevated shell. 



NEITHEA TEXANA. 



Plate V, Figure 2, a, h. 

 Pecten Texanus, Eoemer, Kreide. von Texas, p. 65, pi. VIII, fig. 3. 



Orbiculate-triangular^ plano-convex; inferior valve convex, with 15-17 ribs, which are sub- 

 equal, broad, flattened, smooth, and bisulcate laterally, or margined on each side by a small 

 rib : superior valve flat ; ribs unequal, slightly prominent, flattened. 



Locality. — Between El Paso and Frontera. 



LIMA. 



LIMA WACOENSIS. 



Plate V, Figuke 4, a, h. 

 Lima Wacoensis, Eoemer, Kreide. von Texas, p. 63, pi. VIII, fig. 7. 



Oblong-oblique, transverse, anteriorly subtruncated, with radiating ribs, which are slightly 

 unequal, anteriorly narrower, closer, subdichotomous. 



LIMA LEONENSIS. 



Plate V, Figuke 3, a, b, c. 



Very oblique, elevated, of a somewhat oblong-oval outline ; buccal side produced, compressed, 

 angular at the extremity; margin above the extremity truncated, very oblique; below it the 

 margin is also truncated, and parallel witli the umbonal slope ; basal margin rounded ■ anal 

 extremity angulated ; ears small ; ribs about 19 in number, angular or subangular, and cari- 

 nated on the middle ; surface with fine radiating lines, and towards the base the ribs are more 

 distinctly carinated than above. 



This is a larger species than the preceding, and differs in form, in having carinated ribs, and 

 in having the summit of the right valve much more prominent or elevated than the left ; the 

 ears are also smaller, and the margin much below the summit of the right valve. The lar"-est 

 specimen measures rather more than 1^ inches from beak to anal extremity. 



Locality. — Leon Springs. 



INOCERAMUS, Sowerby. 

 INOCEEAMUS CONFERTIM-ANNULATDS. 



Plate V, Fig. 5. 

 Inoceravius con/ertim-annulatus, Eoemer, Kreide. ton Texas, p. 59, pi. VII, fig. 4. 



Transverse, oval, depressed, concentrically undulato-plicated and striated, folds robust, regu- 

 larly rounded ; intervals of the wider folds hardly equal ; elevated lines very fine, equidistant, 

 regular on the fold, and intervals. 



Locality. — Near New Braunfels. 



