H. W. Shimer — Fossiliferous Miocene Bowlders. 255 



Aet. XYI. — Fossiliferons Miocene Bowlders from Block 

 Island, R. I. ; by Hekvet W. Shimee. 



A fossilifeeous bowlder of rather soft, dark gray argilla- 

 ceous limestone was found in November last upon the beach at 

 Balls Point, the northeast shore of Block Island, by T. A. 

 "Watson and "W. O. Crosby. This rounded bowlder, with a 

 weight of six pounds, is very full of fossils and from it were 

 identified twelve species. The most abundant form was Ostrea ; 

 somewhat less numerous were Cliona, Area, Isocardia and Cor- 

 bula. As is seen from the list below, the fossils indicate a 

 Lower Miocene age, all of the species occurring in the lowest 

 horizon in Maryland, the Calvert, and some of them confined 

 to it. In the list, C = very common, c = common, r = rare, 

 R = very rare, in occurrence in the bowlder. 



Cliona sp. C. Many sponge borings into Ostrea. They 

 are about - 3 mm in diameter and average l mm apart. 



Leda liciata (Conrad), c. 



Corbula cuneata Say. c. 



Tellina sp. R/ Shell when entire was about 30 mm long; it 

 is 15 mm high. Break anterior, within 5 mm of the end of shell. 

 Area well marked. Surface with concentric growth lines. 



Phacoides cf. anodonta Say. R. 



Isocardia cf. mazlea Glenn. C. Somewhat less than one- 

 half the size of the Maryland specimens. 



Area cf. marylandica Conrad. C. The numerous radial 

 strise are not strongly granulated. Ligament area with trans- 

 verse lines, and from the beak, diverging at angle of 120°, 

 extends a furrow, both anteriorly and posteriorly, to the teeth. 

 These are all left valves. About the same number of right 

 valves of an Area are present, but with a decidedly different 

 sculpture. The radial strise are, anteriorly, similar in number 

 but lower and less angular, and upon the posterior slope they 

 disappear entirely. The area was not seen. . These two arcoid 

 forms so similar in form and number, with each confined to 

 one kind of valve, strongly suggest these to be opposite 

 valves of the same species. It is evidently an undescribed 

 form, but I hesitate to make a new species from a bowlder of 

 unknown parentage. 



Ostrea cf. sellseformis thomasii (Conrad). C. Large speci- 

 mens about 50 mm long. The lower valve has a short punctate 

 impressed line near the hinge line ; in the upper valve this is 

 replaced by a transversely denticulate margin confined likewise 

 to the neighborhood of the hinge. 



Turritella plebeia Say. P. 



