NO. 1863. M0LLU8K8 OF THE GENUS ALVANIA—BART8CH. 



337 



is completely shown in the suture, and a slender, spiral thread appears 

 immediately below the summit. The spaces between the keels are 

 about four times as wide as the keels. Suture quite strongly con- 

 stricted. Periphery of the last whorl marked by a strong, spiral 

 keel wliich is a trifle nearer to the first keel posterior to it than that 

 is to its neighbor. Base moderately long, well rounded, narrowly 

 umbihcated, marked by three equal and almost equally spaced spiral 

 keels. In addition to the spiral sculpture, the whorls are marked by 

 numerous, very slender, raised, axial threads which are best developed 

 in the broad spaces between the spiral keels. Aperture subcircular, 

 slightly expanded anteriorly; posterior angle obtuse; outer Hp thin, 

 showing the external sculpture %vithih; inner Hp strongly curved, 

 somewhat reflected; parietal wall covered with a thick callus which 

 joins the posterior angle to the columella and renders the peritreme 

 complete; operculum tliin, corneous. 



The type (Cat. No. 2136S0, U.S.N.M.) and four other specimens 

 were collected at Adakli Island, Alaska. The type has five post- 

 nuclear whorls and measures: Length 4.2 mm., diameter 2 mm. 



Specimens examined. 



Catalogue No. 



161077. 

 2136S1. 

 195372. 

 101100. 

 161002. 

 213683. 

 213682. 

 213680. 



Locality. 



Number 

 of speci- 

 mens. 



Kyska Harbor, Aleutian Islands, Alaska 



Pass, Kyska Harbor, Aleutians, Alaska (10 fathoms, rocky bottom). 



Kvska Harbor, Aleutians, Alaska 



.....do 



Amchitka Island , Aleutians, Alaska 



Constantine Harbor, Amchitka Island, Aleutians, Alaska 



Amchitka Island, Aleutians, Alaska (low water) 



Adakh Island , Alaska (1 = type) 



ALVANIA BAKERI Bartsch. 

 Plate 29, fig. 2. 

 Alvania baJceri Baetsch, Nautilus, vol. 23, 1910, No. 11, p. 137, pi. 11, fig. 8. 

 Shell minute, bluish-white. Nuclear whorls one and one-third 

 forming a moderately elevated spire. Upper half of the well-rounded 

 nuclear whorls marked by about ten very fine, closely spaced, spiral 

 striations ; lower half marked by numerous, closely spaced, depressed, 

 elongate granules, each of which has the long axis decidedly pro- 

 tractively slanted, wliich lends to tliis part of the turn a finely blis- 

 tered appearance. Post-nuclear whorls a Httle more than two, well 

 rounded, separated by a strongly constricted suture, marked by three 

 strong, rounded, spiral keels, of wliich the strongest is a little anterior 

 to the posterior third between the sutures, while the anterior of the 

 other two, wliich are of equal strength, is at the periphery and the 

 tliird halfway between them. In addition to these keels, the whorls 

 94428°— Proc.N.M.vol.41— 11 22 



