LAMELLIBRAXCIIIATA OF THE LOWER MARLS. 63 



valves marked by about twenty to twenty-two narrow, elevated radii, with 

 flattened spaces between, leaving the radii widely separated. Anterior and 

 posterior slopes without radii. 



This species is very like R, reticulata L. & F., but may be readily dis- 

 tinguished by the flattened or occasionally slightly concave spaces between 

 the radii. In other respects the shells are very much alike. 



Formation and locality. — In the Lower Marls at Haddonfield, New Jersey. 

 The specimens used are from the collection of the Academy of Natural Sci- 

 ences, Philadelphia. 



Radula reticulata. 



Plate IX, Figs. 8 and 9. 



Lima reticulata Lyell and Forbes. Quart. Jour. Geo]. Soc, Vol. I, p. 62, 1845, with figures. 



Meek, Check-list S. Inst, p. 7. 

 Ctenoides reticulata Gabb. Synop., p. 114. 

 Badula reticulata (L. and F.) Meek. Geol. Eept. K. J., 1868, p. 725. Stoliczka, Palaeont. 



Indica, YoL III, p. 416. 

 R. denticuticosta (Gabb) Conrad. Am. Jour. Conch., Vol. Y, p. 99, PL IX, Fig. 17. 



f Ctenoides denticuticosta Gabb. Proc. A. N. Sci., Phil., 1861, p. 327. 



Shell small, moderately oblique, strongly ovate, and inflated. Hinge 

 short; beaks proportionally strong, and projecting beyond the cardinal line. 

 Valves nearly equal; anterior margin straight, and not at all gaping; auric- 

 ulations small but distinct, rectangular or verj^ slightly pointed at their outer 

 angles. Surface radiately ribbed, those of the anterior and posterior slopes 

 faintly marked or obsolete, ribs (about thirty) distinct, with five or more 

 indistinct on each side; subangular on the. middle of the valves and rounded 

 toward the sides, crenulate or subspinose on the larger specimens when well 

 preserved, but often appearing nearly smooth. Entire surface marked by 

 concentric lines which give a roughened surface when perfect, giving the 

 reticulated character indicated by the specific name. 



The shells are all small, seldom exceeding three-fourths of an inch in 

 length, and are very fragile. The right valve appears to be a little less ven- 

 tricose and the beak shorter than the left in all the specimens which I have 

 seen where the two are united, still this may be only apparent, as they are all 

 somewhat displaced, and all those which I have seen free from the matrix 

 and separated have the hinge imperfect, so that I have not examined the 



