572 bartsch: northwest coast mollusks 



Alaba catalinensis, sp. nov. 



Shell elongate conic, milk white, early whorls well rounded, the 

 succeeding turns a little less so. All whorls polished, appressed at the 

 summit, and marked by fine retractively slanting lines of growth. 

 Beginning with the second turn, varicial thickenings make their appear- 

 ance; these are ver}^ feeble on the early whorls, but increase steadily 

 in strength until on the last turn they form decidedly raised sinuous 

 ridges. The last whorl, too, shows well marked malleations. Aperture 

 oval; posterior angle obtuse; inner lip curv^ed and reflected, but not 

 appressed to the base; parietal wall covered by a thick callus. 



The type. Cat. No. 213369, U. S. N. M., was collected by Dr. vS. S. 

 Berry in 40 fathoms, off Catalina Island, California. It has ten and 

 a half whorls and measures: length, 5.3 mm.; diameter, 1.9 mm. It is 

 at once distinguished from the other two West American species by 

 the absence of incised spiral lines. 



Cyclostremella concordia, sp. nov. 



Shell ver>' small, planorboid, hyaline, semitransparent. Early 

 whorls eroded in all the specimens seen. Yhe last two whorls curve 

 suddenly to the deeply channeled suture on the upper surface; the rest 

 gradually, evenly rounded. Periphery of the last whorl well rounded, 

 Base openly umblicated. The entire surface of spire and base is marked 

 by rather strong, irregularly developed incremental lines and more or 

 less equal and equally spaced fine spiral lirations. The intersections 

 of these two sculptural elements give to the surface of the shell the 

 characteristic beaded sculpture of the genus. Aperture very broadly 

 ovate, almost subcircular, the narrower portion being at the posterior 

 angle; peristome thin, not reflected; parietal wall covered by a thin 

 callus. Operculum thin, corneous, paucispiral. 



The type and two additional specimens, Cat. No. 340862, U. S. N. 

 M., were collected by Professor Carl C. Engberg at Olga, Washington. 

 The type measures: altitude, i mm.; diameter, 2 mm. Two additional 

 specimens from the same locality are in Professor Engberg' s collection. 

 The Museum also has specimens from Friday Harbor, Washington. 



This species has been known from the last named locality under the 

 names of Skenia, and Skeniopsis planorbis Fabr. 



It is easily distinguished from its nearest neighbor, Cyclostremella 

 californica Bartsch, by its smaller size, more robust form and weaker 

 sculpture. 



