MO'LLUSCA. 447 



below that horizon in New Jersey. It is one of several forms of 

 the type of 0. larva in the New Jersey faunas, and can always be 

 distinguished by its small size and the nonplicate central area 

 of the shell. The number of plications along the convex margin 

 is exceedingly variable, a fact which can be best observed in the 

 larger plications along the lower or convex margin of the shell, 

 excluding the smaller ones near the extremity of the hinge-line, 

 the number varying from four to as many as nine or ten. The 

 species resembles O. pellucida M. & H.^ in its marginal plications, 

 but differs from that species in the presence of the auriculations 

 at the extremities of the hinge-line, and in the small area of at- 

 tachment, although a specimen is occasionally met with that 

 shows that it has been attached for nearly half the length of 

 the shell. 



Formation and locality. — Navesink marl, near Holmdel (127, 

 128^ 194), Oak Hill (121), Atlantic Highlands (108), Middle- 

 town (113^), near Red Bank (120), near Crawfords Corner 

 (126''), Marlboro (131), Crosswicks Creek (149, 147*, 195), 

 near Jacobstown (150), Mullica Hill (169^); Red Bank sand, 

 Shrewsbury River (119, 116) ; Tinton beds. Tin ton Falls (no), 

 near Freehold (132). 



Geographic distribution. — New Jersey. 



Ostrea nasuta Morton. 



Plate XLIIL, Figs. 7-8. 



1834. Ostrea falcata Var. A (0. nasuta) Mort., Synop. Org. 



Rem. Cret. Gr. U. S., p. 51, pi. 9, fig. 6. 

 1 861. Ostrea nasuta Gabb, Synop. Moll. Cret. Form., p. 209 



(153)- 

 1884. Ostrea (Alectryonia) larva\ White (in part), 4th Ann. 



Rep. U. S. G. S., p. 296, pi. 42, figs. 2-5, 9. 

 1886. Ostrea larva var. nasuta Whitf., Pal. N. J., vol. i 



(Monog. U. S. G. S., vol. 9), p. 35, pi. 3, figs. 3-4. 

 1902. Ostrea larva Hill and Vaughan, U. S. G. S., Geol. Atlas, 



Austin Folio, fig. 50. 



' Meek, Rep. Inv., Cret.' and Terr. Foss. Up. Mo., p. is, pi. 28, figs. 4a-4b- 



