358 GEOLOGICAL SUEVEY OF THE TEEEITOEIES. 



Leaia leidyi T. R. Joues. 



Ci/pricardia leidyi Lea, sp. Proceed. Acad. Nat. So. Pliilade]pliia, 1855, 7, p. 341, pi. 4. 



Height of valve, nearly j^ iiicli. ) -pronortion 7 to T> or 1- 1=^ 

 Length of valve, nearly -^ inch, i -t^roportion i to i^, oi i. l^— . 



In the "Proceedings Acad. JSTat. Science of Philadelphia," May, 1855, 

 vol. 7, p. 341, Dr. I. Lea has described a small fossil found by Dr. Leidy 

 in red sandstone at Tumbling Eun Dam, about a mile southeast of Potts- 

 Aalle, in Pennsylvania. The specimen consists of the impression of the 

 outside of the two values. It is figured carefully, of natural size, and 

 enlarged, in plate 4 (op. cit.^), and is named Cypricardia Leidyi by Dr, 

 Lea, who thus describes it: 



" Shell oblong', round before and truncate behind, very inequilateral, 

 striate ; dorsal and basal margins parallel; umbonal slope shortly cari- 

 nate; anterior slope with an elevated line from the back to the basal 

 margin; strise about twelve, very regular, and nearly equidistant (bent 

 at an angle of 90° at the umbonal slope). Length, two-twentieths, 

 breadth, nearly four-twentieths, of an inch." "The shell is accompa- 

 nied on the specimen with some obscure impressed linear marks of a 

 dlant. 



The figures are reproduced here (Plate 5, figs. 11, 12). The sandstone 

 is referred to the formation called l^o. 11 hj Prof. H. 

 D. EiOgers in the State Geological Survey of Penn- 

 sylvania, and referred by him to the base of the Car- 

 boniferous system, but regarded by some geologists 

 as the uppermost part of the Devonian or Old Red 

 Sandstone. In this formation of sandstone (which, 

 with its associated shales, is 3,000 feet thick), foot- 

 tracks of reptiles, rain-prints, wave marks, and trails 

 of annelids or molluscs are not uncommon at two or 



more horizons. rig. 2i.-Leaia leidyi 



Jones then describes as varieties of the foregoing, enlarged. AfterLea. 

 Leaia williamsoniana^ from the ujjpermost coal-measures of Lancashire, 

 England, and L. salteriana, from the lower Carboniferous rocks of Fife- 

 shire, Scotland. 



EsTHERiA DAwsoNi Packard. 



(Plate XXIV, figs. 4, 4 a, 4b.) 



'Estheria dawsoni Packard, American Naturalist, xv, June, 1881, p. 496. 



We have received through the kindness of Principal J. W. Dawson, 

 LL. D., of Montreal, a valve, in partial x)reservation,of an Estheria quite 

 unlike any existing American form. The following account of its dis- 

 covery is from Principal Dawson : 



"It was found at Green's Creek, on the Ottawa River, in nodules in 

 the Post-pliocene clay, holding skeletons of Mallotns villosus and other 

 northern fishes, and shells of Leda (Portlandia) arctica, Saxicava rtic/osaj 

 &c. ; also leaves of Populus, Potamogeton, &c. The deposit is of the 

 age of the Leda clay of the Saint Lawrence (middle glacial) and belongs 

 to a period of submergence where, in the bay or estuary then repre- 

 senting the Ottawa River, northern marine animals were embedded in 

 deposits into which was also washed the debris of neighboring land, 

 and of fresh-water streams. The climate at the time was colder than 

 at present, and the area of land less, so that, if this Estheria still lives, 

 it is most likely to be found in the vicinity of the Arctic coast." 



This Estheria is entirely unlike any northern American or European 



