112 PALEONTOLOGY OF NEW JERSEY. 



pasted on the inside, so that I cannot actually examine the entire surface. 

 This species is the type of the genus Nucularia, of which I have been 

 unable to find a generic description. It is placed by its author under the 

 family Nuculanidce, but so far as the shells themselves afford evidence of 

 their structure, I feel quite doubtful if it belongs here at all. If so, it must 

 be quite near Mellitia. 



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

 Beds at Haddonfield, New Jersey. 



TRIGONID^. 



Genus TEIGONIA Brug. 



Trigonia Mortoni, u. sp. 



Plate XIV, Figs. 5 and 6. 



Trigonia thoracica Mort. Pars., SyDopsis, p. Go. Gabb, Synopsis, p. 177. Meek, 

 Check-list, p. 9. Geol. Surv. K J., 1808, p. 725. 



Species known principally as casts of the interior, which are subtrian- 

 gular in outhne, prolonged posteriorly and narrowed; the body standing 

 nearly at right angles to the beaks and umbonal portions. Anterior end in- 

 flated, compressed, and almost attenuate posteriorly; filling of the beaks 

 erect, scarcely incurved, and quite distant. Anterior muscular fillings large, 

 prominent, and giving evidence of extremely deep impressions in the shell. 

 Postei'ior scars moderately prominent, circular, or nearly so, submarginal 

 and accompanied by a small secondary or pedal scar on the upper side 

 nearer the hinge. Surface of the cast usually marked near the margin with 

 strong, rather distant undulations, indicating strong curved costse, of which 

 there can be counted on some specimens ten or twelve, usuall}^ indicated 

 only on the basal half of the valve, but rarely seen crossing the rostral por- 

 tions of the cast and strongly arching upwards as they approach the margin. 

 The postero-cardinal area has been comparatively narrow, and the casts 

 usually show a single strong undulation on the upper side of the umbonal 

 i-idge, near the posterior extremity. 



A single fragment of green marl retaining the impression of a part of 

 tlie exterior of a shell has been obtained, which shows that the original form , 



