456 THE CHICAGO ACADEMY OF SCIENCES. 



Westerlund's original Latin description is as follows: 



"Testa aperte rimata, elongata, tenuis, fragilis, pellucida, irregu- 

 lariter striatula, pallide cornea, spira longa, supra anfractum penulti- 

 mum tumidum abrupte angustata, valde contorta, apice acuta; anfr. 

 6, perconvexi, sutura profundissima perobliqua disjunct!, superne sub- 

 truncati, tumidi, basin versus forte declivi, attenuati; apertura dimid- 

 iam testae non attingens, verticalis, subsemicircularis, margine exteriore 

 forte arcuato, superne sinuato, medio producto, (columella cum) mar- 

 gine columellari substricto; verticali, late reflexo, umbilicum semite- 

 gente; columella incisura obliqua sat profunda, plica lata appressa." 



Westerlund compares his species with Galba traski Tryon but is irr 

 error as that species belongs to a different group. 



Galba petersi (Ball). Plate XXX, figure 29. 



Lymneea petersi DALL, Alaska Moll., p. 66, pi. 2, fig. 3, 1905. PILSBRY, 

 Nautilus, XIX, p. 95, 1905. 



"SHELL : Extremely thin, of five or more tumid rapidly enlarg- 

 ing whorls ; spire acute, the sutures deep ; whorls rounded, the periph- 

 ery nearer the preceding suture; shell of a blackish brown, polished, 

 finely, sharply, spirally striate; periostracum brownish, darker at rest- 

 ing stages ; aperture oval, a thin wash of callus on the body ; pillar very 

 thin, gyrate, the gyrations pervious; the outer lip not thickened." 



Height. Breadth. Aperture length. Breadth. 

 16.00 8.00 8.50 5.20 mill. Type. 



TYPES: Smithsonian Institution, two specimens, No. 180332. 



TYPE LOCALITY : Koyukuk River, north of the Yukon in Alaska. 



ANIMAL, JAW, RADULA and GENITALIA: Unknown. 



RANGE : Alaska, north of Yukon River ; a species of the Yukon- 

 ian region. 



RECORDS. 



Koyukuk River, north of the Yukon in Alaska (W. J. Peters). 



GEOLOGICAL RANGE: Unknown. 



ECOLOGY: Not recorded. 



REMARKS: "This very delicate and pretty species appears to be- 

 long to the typical Lymncea in spite of its small size; it has much the 

 aspect of a minute L. randolphi, but has more whorls in less than half 

 the height and is of quite a different color and without angularity to 

 the whorls." (Dall). 



Petersi can scarcely belong to the typical Lymnseas. Its close re- 

 semblance to young specimens of Galba randolphi would lead to the 

 assumption that its proper position is near that species. A camparison 



