30 



SHORTER ClONTRIBUTIONS TO GENERAL GEOLOGY, 1919. 



The differences of size, form, and geographic 

 distribution seem to be conclusive as to the 

 specific distinction between Littorina obtu- 

 sata and Littorina palliata. They are not Arc- 

 tic shells. 



Crypioctenidia magna Dall, n. sp. 



Plate V, figure 1. 



Shell large for the genus, ovate, apex very 

 anterior, the back behind it roundly arched, 

 the anterior slope more steeply descending; the 

 apex blunt, usuallj" eroded; sculpture of fine 

 radiating tlireads with subequal interspaces, 

 more or less cut into segments by incised lines 

 corresponding to resting stages and equally 

 distributed over the shell; interior white, the 

 margins entire, smooth; the muscular impres- 

 sion narrow, connected in front of the head by 

 a linear scar indicating the attachment of the 

 mantle. Height, 10 millimeters; length, 29 

 millimeters; breadth, 25 millimeters; apex be- 

 hind the anterior margin, 5 millimeters, A 

 defective specimen measures 34 millimeters 

 long and 29 millimeters wide. 



Stations 5074, 5078, and 7619. Pliocene 

 of Center Creek, 1^ miles north of Nome, from 

 the "second beach, " collected by E. M. Kindle. 

 Also from prospect holes on the second beach, 

 one-fourth to one-half mile east of Nome; and 

 from Center Creek mines 2 miles northwest 

 of Nome. Collected by E. M. Kindle and R. D. 

 Mesler, 1908. U. S. Nat. Mus. catalogue No. 

 324320. 



The species of this genus are very similar to 

 one another, but this is larger than any of the 

 recent forms and differe in details of sculpture, 



Cadulus arcticus Dall, n. sp. 



Plate V, figure 8. 



Shell small, slender, arcuate, smooth, with 

 chcular section and no swelling ventrally; the 

 color is white with narrow translucent zones 

 u-regularly disposed. Length, 7 millimeters; 

 diameter at anterior end, 0,75 millimeter; 

 height of arc described by the ventral curve, 

 1,2 millimeters. 



Station 7070, Pliocene of Carter Creek, in 

 the Camden Bay region of the Ai'ctic coast, 

 stratum C, 100 feet below stratum B and 600 

 feet east of station 7069, 1 mile from the coast. 

 Collected by E. de K. Leffuigwell, 1914. U. S. 

 Nat. Mus. catalogue No. 324322. 



Tliis stratum, from the collector's notes, 

 seems to be some 220 feet })elow the uppermost 

 stratum of the section. 



PELECYPODA. 

 Pecten (Chlamys) kindle! Dall, n. sp. 



Plate VI, figures 2, 7. 



Shell large, rather rude, belonging to the 

 group of Pecten swlfti Bernardi, Right valve 

 with four broad, low radial ribs separated by 

 much narrower, shallow, ill-defined intcrspa- 

 tial furrows; the whole surface sculptured with 

 strong radial, more or less paired flattish cords, 

 often minutely medially grooved and some- 

 times separating into two distinct radii; the 

 interspaces are about as wide as the cords and 

 distinctly channeled; they also retain patches 

 of a minute reticulated surface lamella tion; 

 the beak is pointed, the anterior ear large, 

 aliform, with an acute but not deep notch, 

 leaving a broad concentrically laminate fasci- 

 ole, the margin of the disk at the notch with a 

 ctenolium of two or tlu-ee rather widely sepa- 

 rated short spinules; the rachal threads crossed 

 by rather coarse incremental lines; the pos- 

 terior ear is very short, narrow, and oblique; 

 imier surface of the valve smooth except near 

 the distal margin, where it reflects the external 

 sculpture; the adductor scar large, the resil- 

 iary pit rather small for the size of the shell, 

 with the lateral margins raised; a narrow, 

 transversely striated area exists, broader on 

 the left valve; there are no auricular crura. 

 Left valve with five narrow radial ribs sepa- 

 rated by wider shallow interspaces which are 

 wider on the posterior half of the disk; the sur- 

 face is covered with radial cords as in the other 

 valve, but these are finer and closely crowded 

 on the submargins ; the reticular surface layer 

 is the same as in the left valve, but the right 

 valve as usual is more convex; anterior ear 

 triangular, large, with about eight or ten radial 

 cords; posterior ear narrow and short; both set 

 off from the submargins of the disk by a deep, 

 wide furrow; hinge line straight, with a flat 

 area half as wide as the length of the pit. The 

 young valves retain a reddish tinge in their 

 substance. Height of adult valve, 92 milli- 

 meters; width of disk, 78 millimeters; of hinge 

 hne, 45 millimeters; diameter, 27 millimeters. 



Station 7(319, Pliocene of Center Creek 

 mines, 2 miles north of Nome, from the 



