114 PALJEO^^TOLOGY OF ^'E^V JERSEY. 



the shell at right angles with the lunule, exhibiting a tendency to being no- 

 dose, especially near the luniile; lunule marked by ten or twelve transverse- 

 ribs; cardinal margin somewhat incurved, anterior end subtriangular, basal 

 sinuous and deeply serrate, posterior regularly rounded ; internally, hinge 

 teeth small; muscular impressions deep; palHal line entire; a small tooth- 

 like ridge or process extends along the middle of the alation, as in T. alcE- 



formisr 



The above description is in some particulars rather incomprehensible,, 

 from the reversal of the anterior and posterior of the shell, as usuall}' given 

 by other authors. If these are considered it is much more lucid; and in 

 the same way that which is termed the lunule would be the area bordering 

 the cardinal line. The species very closely resembles what young individ- 

 uals of T. tJioracica must have been, but appears to possess more ribs pro- 

 portionately for the size of the specimens. At the typical locality (Eufaula, 

 Ala.) the specimens are always quite small, and considerably prolonged 

 behind, with the basal margin strongly denticulated by the projection of 

 the ribs The small cast figured has a larger number of ribs proportionally 

 than have those from near Red Bank, one of which is also figured, and is 

 more distinctly removed specifically from T. tJioracica Morton. 



Formation and locality. — In the micaceous clays of the Lower Marl 

 Beds, at the "crossing of the West Jersey Railroad at a creek between Red 

 Bank and Gloucester, N. J.," and in the green marls in Monmouth County. 

 The former are from the collection of the Academy of Natural Sciences of 

 Philadelphia, and the latter from the collection at Rutgers College. 



Trigonia cenilia, ii. sp. 

 Plate XIV, Fig. 7. 



Shell small or below a medium size, moderately convex on the valves 

 and of a triangularly-ovate outline. Beak small, appressed, obtusely pointed 

 and erect ; posterior hinge-line long and -slightly concave ; posterior end 

 narrow and rounded ; anterior end broadly rounded ; basal line a little gib- 

 bous in the middle, but otherwise forming a continuous line with the ante- 

 rior and posterior margins. Surface of the shell covered by coarse elevated 

 ribs, which are flattened on their surfaces over a large part of the shell, but 



