218 



UNITED STATES NATIONAL MUSEUM BULLETIN 215 



1,967-1,977 feet, unfigured paratypes (USNM P4610) 

 from a core at 2,024-2,026 feet, and figured paratypes 

 (USNM P4611a,b) from well cuttings at 2,390-2,395 

 feet, all from the Topagoruk formation ; all from Simp- 

 son test well 1, at lat. 70°57'05" N., long. 155°21'45" 

 W., west of Cape Simpson, northern Alaska. 



Unfigured paratypes (USNM P4612) from well 

 cuttings at 4,180-4,190 feet, unfigm-ed paratypes 

 (USNM P4613) from well cuttings at 4,220-4,230 

 feet, unfigured paratypes (USNM P4614) from well 

 cuttings at 4,340^,350 feet, all from the Topagoruk 

 formation, in Umiat test well 1, at lat. 69°23'52" N., 

 long. 152°19'45" W., west of Umiat, in the northern 

 foothills of the Brooks Kange, northern Alaska. 



Unfigured paratypes (USNM P4615) from well 

 cuttings at 4,140-4,150 feet and unfigured paratypes 

 (USNM P4616) from a core at 5,585-5,595 feet in the 

 Topagoruk formation in Umiat test well 2, at lat. 

 69°23'04" N., long. 152°05'01" W., north of Umiat, 

 in the northern foothills of the Brooks Range, northern 

 Alaska. 



Unfigured paratypes (USNM P4617) from 2,390 

 feet below the top of the Grandstand formation (field 

 sample 47 A Dt 227), about 4% miles airline upstream 

 from the mouth of Fossil Creek, a small north-flowing 

 tributary to the Colville River, at approximately lat. 

 69°19'20" N., long. 152°28' W., in the northern foot- 

 hills of the Brooks Range, northern Alaska. Collected 

 by R. L. Detterman, 1947. 



Unfigured paratypes (USNM P4618) from the lower 

 part of a 50-foot section of the Topagoruk formation 

 (field sample 47A Tr 167) on the west fork of Birthday 

 Creek, at approximately lat. 69°12'30" N., long. 

 156°47' W., which flows south into the Awtma River, 

 north-central Alaska. Collected by M. L. Troyer, 

 1947. 



Euiycheilostoma robinsonae Tappan, new species 

 Plate 70, Figures 8-11 



Test free, trochoid, conical, dorsal side in a much 

 elevated spire of about fom* volutions, ventral side 

 concave with open and extensive umbilicus, periphery 

 rounded; chambers inflated, increasing rapidly in size, 

 later ones becoming semilunar in dorsal view but 

 relatively high as seen in edge view, final whorl with 

 only three chambers, the last chamber occupying about 

 three-fifths the area of the ventral side ; sutiu-es distinct, 

 slightly depressed; wall calcareous, finely but distinctly 

 perforate, surface smooth; aperture ventral, an arch 

 at the inner margin of the final chamber, opening into 

 the umbilicus and partly covered by a ventral umbilical 

 flap of the chamber, which has a serrated border, and 

 an apertm'al reentrant into the chamber face at each 

 extremity of the flap. 



Greatest diameter of holotjnpe 0.29 mm., height of 

 spire 0.31 mm. Paratypes range from 0.13 to 0.29 nam. 

 in diamter. 



Remarks: Eurycheilostortia robinsonae, new species, 

 differs from the associated E. grandstandensis in the 

 much lower spire and more regular increase in chamber 



size. It differs from E. altispira Loeblich and Tappan 

 in being about twice as large and higher spired. 



This species is foimd in the Grandstand and Topa- 

 goruk formations. The specific name is given in honor 

 of Florence Robinson, geologist, U. S. Geological 

 Survey. 



Types and occurrence: Holotype (USNM P4584) 

 and unfigiu-ed paratypes (USNM P4585) from a core 

 at 651-661 feet in the Topagoruk formation, in Arcon 

 Point Barrow core test 1, at lat. 71°19'30" N., long. 

 156°40' W., southwest of Point Barrow, northern 

 Alaska. 



Figm-ed paratype (USNM P4586) from a core at 

 264 feet in the Grandstand formation, in Skull Clifi 

 core test 1, at lat. 70°55' N., long. 157°38' W., between 

 Point Barrow and Point Franklin, northern Alaska. 



Figured paratype (USNM P4587) and unfigured 

 paratypes (USNM P4588) from a core at 2,024-2,026 

 feet, unfigured paratypes (USNM P4589) from well 

 cuttings at 1,760-1,770 feet, and unfigured paratypes 

 (USNM P4590) from well cuttings at 1,840-1,850 feet, 

 all in the Topagoruk formation, in Simpson test well 1, 

 at lat. 70°57'05" N., long. 155°21'45" W., west of 

 Cape Simpson, northern Alaska. 



Figured paratype (USNM P4591) and unfigured 

 paratypes (USNM P4592) from a marine zone at the 

 base of a 640-foot section, in an unnamed, dominantly 

 marine lower unit of the Nanushuk group found in 

 the western area (field sample 47 A Ba 67), on the north 

 limb of a syncline, just north of the Utukok River and 

 southwest of a small tributary at approximately lat. 

 69°14' N., long. 160°37' W., about 70 miles east- 

 northeast of Cape Beaufort, in the northern foothills 

 of the Brooks Range, northern Alaska. Collected by 

 W. L. Barksdale, 1947. 



Genus Nanushukella Tappan, new genus 



Type species: Nanushukella umiatensis Tappan, 

 new species. (Derivation: Nanushuk, formational 

 group in Alaska -1- ella, L., diminutive; gender, 

 feminine.) 



Test free, trochoid, planoconvex, low spired, ven- 

 trally umbilicate, periphery rounded; all chambers 

 visible on the convex dorsal side, only the relatively 

 few of the last whorl visible ventrally; sutures dis- 

 tinct, oblique dorsally, radiate ventrally; wall calcare- 

 ous, relatively coarsely perforate, surface smooth; 

 aperture ventral, a low arch along the broad umbilical 

 margin of the final chamber and opening into the 

 umbilicus, with a narrow fimbriate lip or flap extending 

 its full length, the apertures of all earlier chambers 

 of the final whorl remaining open beneath their flaps 

 along the sutures from the umbilicus about one-half 

 the distance to the periphery. 



Remarks: Nanushukella, new genus, differs from 

 Conorhina Brotzen in having a more extensive umbilical 

 aperture and an open umbilicus and in having all 

 earlier apertures of the final whorl remaining open. 



