128 THE CHICAGO ACADEMY OF SCIENCES. 



"Shell ventricose, with a short acute spire and few rounded whorls, 

 rugose, umbilicate, the last whorl ample, with a rotund transverse 

 aperture, and continuous peristome appressed on the columellar mar- 

 gin; the outer lip simple" (Dall). 



The type is Zagrabica naticoides BRUSINA, a Pleistocene fossil. Ac- 

 cording to Dr. Dall, Dybowski has referred to this group a recent 

 species from the Caspian Sea under the name of Z. brusiniana. As 

 remarked by Dall, this group appears from the description to be 

 related to Radix. 



Velutinopsis SANDBERGER, Land und siissev. Conch, d. Vorwelt, p. 700, 1875. 

 TRYON, S. & S. Conch., Ill, p. 101, 1884. DALL, Alaska Moll., p. 63, 1905. 



"Shell almost planorboid, with but few, rounded, rapidly increasing 

 whorls ; the aperture simple, suborbicular, the peristome sharp, simple, 

 not reflected ; the pillar lip broad, not appressed ; the axis umbilicate" 

 (Dall). Type, Lymnaa velutina DESHAYES, from the Pliocene of the 

 Crimea. 



As remarked by Dr. Dall, this fossil genus looks like Choanom- 

 phalus, and it probably belongs with Pompholy.v and Carinifc.v, and 

 not to the Lymnseidae. 



Erinna H. and H. ADAMS, Gen. Rec. Moll., II, p. 644, 1858. DALL, Ann. 

 Lye. N. H., IX, p. 350, 1870. TRYON, S. & S. Conch., Ill, p. 102, 1884. DALL, 

 Alaska Moll., p. 63, 1905. 



"Shell small, with a short spire, a large final whorl ; the aperture 

 with a continuous peristome which passes behind a broad, somewhat 

 excavated pillar; axis imperforate and the pillar plicate" (Dall). Type, 

 Erinna newcombi ADAMS, from the Hawaiian Islands. 



This group has been modified, as stated by Dr. Dall, by its habit 

 of living on rocks in swiftly running water or in waterfalls ; this modi- 

 fication causing the spire to shorten up, the aperture to become ex- 

 panded and the inner lip to be continued over the body whorl, providing 

 a flat basal surface enabling the animal to cling tightly to its rocky 

 support. 



Physastra TAPPARONE-CANEFRF, Ann. Mus. Genov., XIX, p. 245, 1883. 

 DALL, Alaska Moll., p. 64, 1905. 



"Shell like Stagnicola, but with a coarse dehiscent periostracum, 

 and coiled sinistrally" (Dall). Type, Physastra vestita TAPPARONE- 

 CANEFRI, from New Guinea. 



The reversed Lymnaeids from Polynesia will probably fall into this 

 genus, which will doubtless be found to possess distinctive characters, 

 in the genitalia and radula. 



