MIOCENE MOLLUSCA AND CEUSTACEA. 49 



Genius AXIN^A Poll. 



AXINEA LENTIFORJIISI 



Plate VII, tigs. .J and 6. 



Pectiiiwultis lenti/ormis Ooiirad: Foss. Shells Tert. formatious U. S., p. 36; Mioeeue 

 Foss., p. (U, PI. XXXVI, fig. 1 ; Taomey & Holmes, Pliocene Foss. S. C, p. 4:8, 

 PI. XVII, fig. li; Euiiuous, Geol. N. Car., p. 286; Heilpriu, Acad. Nat. Sci. Pbil., 

 1887, p. 402. 

 ' Axinea lentiformin Couvdd: Proc. Acad. Nat. Sci., Phil., 1861', p. 580; Meek, Check 

 List, X). 5. 



Coiu-ad gives a description of this species in his Fossils of the Median 

 Tertiary, p. 64, as follows: "Lentiform, thick and ponderous, with fine, 

 (•losely arranged, radiating lines, and distant mm'e profound lines, giving the 

 shell a slightly ribhed aspect; valves widest above or across the base of the 

 uinbones, where the margins are rather obtusely niunded; umbo large, and 

 the summit prominent; dorsal margins obli(|ue, curved; cardinal plate 

 dilated, the teeth \ery large and ol)lique; marginal crena^ rather narrow 

 and a])proximate." 



The specimens of Axiuea which have come tome from the New Jersey 

 beds are all small, young individuals; the largest being scarcelv more 

 than five-eighths of an inch in width — so small in tact that thev scarcely 

 show the true specific features, and I am some^^ hat in doubt as to which of 

 these species to refer them, A. Jeiitifunnis, A. patUi.s, or A. paam. The 

 shells are more circ-ular in outline than anv of the three except A. parUis, 

 while the teeth more nearly resemljle those of A. IcHtiforniis than of either 

 of the others, lieing proportionally large and very distinct, while the inner 

 extremities are very slightly inclined. In A. parilis and in A. passa, the 

 teeth are shorter than in the otlier, and are each more distinctly bent when 

 the shells are fully grown; but in young specimens fnjni Yorktown it is 

 nearly impossible to distinguish the specific features. The surface of the 

 New Jersey specimens more closely resembles that of A. parllls than of 

 an}' of the others, as the ribs are flat, with a simph' impressed line dividing 

 them, with about five longitudinal stria; on each; while in the other species 

 they are usually more rounded and prominent. Taking all these features 



31QX XXIV 4 



