b PROCEEDINGS OF THE NATIONAL MUSEUM vol.74 



FOSSARUS (ISAPIS) URBANNAENSIS. new species 



Plate 1, figures 2, 8 



Shell large, turbinate, tabulated at the shoulder, spire high for 

 genus, consisting of about three whorls, early whorls decorticated. 

 Suture deep and grooved. Spiral sculpture on body whorl consists of 

 a faint line on the posterior slope and three strong elevated, equally- 

 spaced ridges on the periphery, the posterior two being weaker and 

 slightly marginally reflected, the anterior one stronger, nearly flat- 

 topped, and coronated. Base with three spirals, anterior two 

 stronger ; anterior one surrounds the umbilicus. Fine granulose spi- 

 rals override the strong ridges and the irregular transverse growth 

 lines. Aperture nearly round, axial diameter a little greater. 

 Outer margin of aperture undulating in conformity to spiral sculp- 

 ture, inner margin slightly reflected over the umbilicus. 



Dimensions. — Type (Cat. No. 352439, U.S.N.M.), altitude, 7 mm.; 

 diameter, above the aperture, 5.2 mm.; axial diameter of aperture, 

 3.5 mm. 



Type locality. — U. S. G. S. station 3915, river front at Urbanna, 

 Va. (Frank Burns, collector, 1903.) 



Fossarus dalli Whitfield is related to the new species but lacks the 

 fine granulose spirals, has a less angled basal slope, and stronger 

 transverse sculpture crossing the strong spirals. 



Occurrence. — St. Marys formation, zone 2. Known only from 

 type locality. 



Class PELECYPODA 



PECTEN EBOREUS URBANNAENSIS, new subspecies 



Plate 2, figure 2 ; plate 3, figure 2 



The type locality of Pecten ehoreus Conrad ^ is Sujffolk, Va. Dall ^ 

 classified different mutations of the species and designated each by 

 a varietal name. The form occurring at Suffolk he designated Pec- 

 ten ehoreus ehoreus. 



The new subspecies differs from the Suffolk form as follows : The 

 ribs are lower and are separated by a shallower and less distinct in- 

 terspace. Two to three fine radials lie within these interspaces. 

 The ears are larger, the byssal notch deeper, and the radials on the 

 ears are finer and less distinct. The new subspecies is an intermedi- 

 ate form between P. iiiadisonius Say and P. ehoreus ehoreus Conrad. 



Dimensions. — Cotypes (Cat. No. 370829, U.S.N.M.), right valve, 

 latitude, 107 mm. ; altitude, 97 mm. ; diameter, 17 mm. Left valve of 



* Conrad, T. A., Amer. Journ. Sci., ser. 1, vol. 23, p. 341, 1833. 



' Dall, W. H., Wagner Free lust. Sci. Trans., vol. 3, pt. 4, p. 750, 1898. 



