INSTITUTE OF SCIENCE, PHILADELPHIA. 39I 



Zizyphinus philantkropus Conr., Proc. Acad. Nat. Sci. 1S62, p. 569; Meek, Checklist 

 Miocene Fos. U. S., p. 15, 1S64. 



Miocene of Calvert Cliffs, Calvert Co., and Jones's Wharf, St. Mary's Co., 

 Md., Burns ; of James River, Va., Conrad ; Petersburg, Va., Lea; near York- 

 town at various localities, Harris and Darton ; Cape Fear River, at Mrs. 

 Guion's marl-bed, Johnson ; Darlington, S. C, Tuomey and Holmes. 



A specimen of this species and one of T. RlitchelH Conr. were found in 

 the same tray at the Academy, with a label in Conrad's handwriting bearing 

 one name on one side and the other name on the other side of one and the 

 same slip of paper. As the specimens agree with the traditionary identifica- 

 tion of the two species, there can be little question as to their authenticity. 



This is, perhaps, the most common species of the Virginia Miocene, and 

 grows to the size of 19 to 20 mm. high and wide. The most usual form is char- 

 acterized by, on the early whorls, three subequal beaded spirals, which have 

 much wider, smooth interspaces, in which a single plain smaller thread 

 gradually appears. The periphery is squared, or even channelled, the pos- 

 terior angle being formed by a strong, plain rib, the basal angle by one more 

 feeble, and there may or may not be several finer threads in the channel. In 

 old specimens the channel is obsolete, the periphery rounded and finely spiral- 

 ly threaded. The base is furnished with half a dozen wide, flattish spirals 

 outside of the umbilical region, beyond which the threads are smaller. The 

 umbilical region is slightly excavated, but imperforate. The suture is 

 appressed, and runs on the basal keel of the periphery. The upper part of the 

 whorls is subconcave or slightly impressed. The beaded spirals sometimes 

 lose their pustules, that thread which is next the suture behind retaining them 

 longest. Young specimens often have the middle of the base smooth, flat, 

 and destitute of spirals. 



Oalliostoma philanthropus var. eliminatum Dall. 

 Plate 18, figure 9. 



Newer Miocene of the Cape Fear River, Johnson, from Mrs. Guion's 

 marl-bed. 



Shell depressed conic, of about six whorls ; nucleus lost in the speci- 

 men ; upper surface of the whorls marked by a single beaded raised line near 

 the posterior suture, and by another not quite so near the anterior suture; on 

 the latter the beading becomes more or less obsolete on the last whorl ; be- 

 tween the two beaded lines the surface is concave and obscurely spirally striate ; 

 sutures distinct ; base somewhat flattened, not umbilicate, but with two wavy 

 or beaded strong spiral bands about the umbilical region ; outside of these 

 are four others successively smaller and more adjacent, beyond which the sur- 

 face is obscurely striate to the periphery ; between the primary lines first men- 

 tioned the interspaces show fine intercalary threads, two to four in each ; um- 

 bilical region depressed, callous ; pillar short, concavely arched, smooth ; outer 



