MOLLUSCA. 383 



point at about the mid-height of the shell; basal margin gently 

 convex, subparallel with the posterior part of the hinge-line; 

 posterior margin rounding from the posterior extremity of the 

 hinge-line, the greatest posterior extension of the shell being 

 abo've the middle, obliquely convex, subtruncate below and round- 

 ing into the basal margin. Surface of the shell nearly smooth, 

 marked only by faint concentric lines of growth. 



Remarks. — The types of this species from Haddonfield are 

 scarcely more than one-half the size of the specimens whose 

 dimensions are given above. This fact, however, is in accord 

 with the individuals of many of the Haddonfield species, which 

 grow to a much larger size in the more northern localities. The 

 hinge characters of the Haddonfield specimens have never been 

 properly made out ; the fragmentary shells preserving imperfectly 

 the hinge-teeth assigned to this species, and made typical of the 

 genus Nitcidaria belong without doubt to some other species as 

 has been suggested by Whitfield. The internal cast from near 

 Matawan, which is here illustrated, agrees in all the general 

 characters of the shell, except size^ with the typical Haddonfield 

 specimens, and there can be no doubt as to their specific identity, 

 but this Matawan specimen preserves very perfectly an impression 

 of the hinge-plate, which shows the dentition tO' be not funda- 

 mentally different froirn that of the associated Yoldia longifrons. 

 The presence or absence of the deep pallial sinus has not been 

 detected in any of the specimens observed, so that it has not been 

 absolutely demonstrated that the species is a member of the geflus 

 Yoldia, but when the strong general similarity with Y. longifrons 

 is taken into account, there is little or no doubt as to its proper 

 generic position. 



Formation and locality. — Woodbury clay, near Matawan 

 (103), near Haddonfield (183, 165, 164). 



Geographic distribution. — New Jersey. 



Yoldia cliffwoodensis n. sp. 



Plate XXX., Figs. 3-4. 



1905. Yoldi cf. evansi Weller, Jour. Geol., vol. 13, pp. 239, 331 ; 

 also Ann. Rep. State Geol. N. J., for 1904, pp. 137; 

 138. (Not Y. evansi M. & H.) 



