154 



SCIENCE. 



[N. S. Vol. XV. No. 369. 



sis or more, deeply sutured and exhibiting 

 strong growth striae. Apex whorls closely and 

 slightly pitted. Aperture and umbilical 

 region covered by a portion of the matrix in 

 which the shell was imbedded. 



Diameter (maximum), 24 mm., probably 26 

 to 26i mm. when perfect. Elevation, about 

 10 mm. A sufficient portion of the shelly sub- 

 stance intact admits of the above description. 

 Number of specimens, six; of these the indi- 

 vidual described is the largest and most per- 

 fect. The smaller examples consist mainly of 

 the upper whorls. 



With more and better material it is quite 

 probable the foregoing might prove to be an 

 angulated, dwarfed, depressed aspect of the 

 living fideliSj or mormonum; it also suggests 

 the form known as Hillehrandi. Nearly all 

 of the material is in a very unsatisfactory con- 

 dition, with no color indications to assist in 

 determination. While for these reasons the 

 conclusions may be regarded as more or less 

 arbitrary, the general character and relation- 

 ship is believed to be fairly well pointed out. 



PYRAMIDULA LECONTEI N. S. 



Shell small, orbicularly depressed, widely 

 and deeply um.bilicated ; whorls four and a 

 half to five, rounded, closely and conspicuously 

 ribbed except on the apex, which is nearly 

 smooth; the ribbing extending into the umbil- 

 ical cavity ; the grooves between the ribs nearly 

 as wide as the ribs are thick ; the suture deep ; 

 aperture nearly circular or rounded lunate; 

 edge of lip simple. Diameter (maximum), 8J 

 mm. Elevation, nearly 5 mm. A single ex- 

 ample; the last whorl has been broken back 

 somewhat; the maximum diameter was prob- 

 ably 9 to 9 J mm. The specimen appears to be 

 scarcely mature. The number, prominence 

 and regularity of the ribs make this a very 

 pretty shell. The general facies suggests rela- 

 tionship with the extraordinary group of 

 helicoid forms that are so widely distributed 

 throughout the vast area denominated by Mr. 

 W. G. Binney* the 'Central Province,' and 

 listed by Dr. Pilsbry in his recent catalogue, 

 as number 340f (P. strigosa and numerous 



• ' Manual of American Land Shells,' Bull. 18, 

 U. S. National Museum. 



t ' Classified Catalogue of Land Shells of North 

 America,' etc., Philadelphia, April, 1898. 



races or varieties). A comparison of P. Le- 

 Gontei kindly made for me by Professor Dall, 

 with the large series of the strigosa group in 

 the National Museum, determines it, as he 

 says, to be 'different from anything we have 

 in the collection.' 



In memory of the late Professor Joseph Le 

 Conte, I have attached his name to the above 

 form. 



In addition to the species herein described, 

 the material submitted to me by Professor 

 Merriam included a small globose form about 

 the size of a small pea; there are several ex- 

 amples, so disguised by adherent particles of 

 matrix as to make it doubtful whether they 

 belong to terrestrial or aquatic groups, with a 

 presumption in favor of the first. 



Partially exposed in portions of a fine com- 

 pressed sediment of lacustrine origin are sev- 

 eral casts of a very large Limncea, suggestive 

 in a general way of the circumboreal L. stag- 

 nalis, but so much distorted as to preclude a 

 more definite description. For convenience 

 this may be knovm provisionally as L. maxima. 



Professor Merriam has now in preparation 

 a paper on the paleontology of the John Day 

 region, which will contain in detail the special 

 data relating to the occurrence of the various 

 forms above referred to as well as figures of 

 the species I have described. 



EoBT. E. C. Stearns. 



CURRENT NOTES ON PHYSIOGRAPHY. 



THE ISTHMUS OF PANAMA. 



An essay on the 'Geology of the Central Por- 

 tion of the Isthmus of Panama,' by Hershey 

 {Bull. Dept. Geol. Univ. Cal., II., 1901, 231- 

 267), includes an account of the surface fea- 

 tures in terms of the two chief cycles of de- 

 nudation that have had effect there. The 

 axial Cordillera de Veraguas, trending east 

 and west, is described as a dissected plateau 

 whose general surface, once a lowland of deg- 

 radation, consisting in part of syenite and 

 intrusive volcanic rocks, is now raised to an 

 altitude of 3,000 feet. The valleys in it are 

 deep, narrow, and steep-sided. Eliminating 

 them, the district would be a high plateau 

 with a width of 20 or 25 miles, arched a little 

 along an east-west medial line, but otherwise 



