228 The Molluscan Family Planorbidae 



ture. Some individuals of costata may have slightly membranous ribs, but 

 these are never like those of dalli. 



Type Locality. Klamath Falls, Oregon. 



Type Material. Seventeen specimens, collected by Henshaw, are de- 

 posited in the United States National Museum, Accession no. 219749. The 

 holotype is figured on plate 115 as fig. 27; paratypes as figs. 28-30. 



Parapholyx klamathensis sinitsini, New Variety 

 Plate 123, lig.^. 2-10 



Shell similar to that of klamathensis but smaller, more globose; the shell 

 thicker and more solid. Spire more elevated than in typical klamathensis; 

 aperture rounder, not as effuse; columella callus heavier, more tightly ap- 

 pressed to the columella. The umbilicus usually closed, rarely having a 

 small chink. Color brownish horn, never greenish. Sculpture heavier than in 

 klamathensis, growth lines more distinct, in a few specimens rib-like. In- 

 terior of aperture reddish-brown. Lip bordered internally by a white 

 margin which in old specimens forms a thickened callus. In contrast, 

 klamathensis of typical variety has a thin lip without a callus. Columellar 

 callus white. Whorls three. Some specimens with diagonal markings like 

 pores. Aperture angulate below, as in klamathensis, but not markedly 

 angular in some specimens. 



Type Locality. Bercley Spring, fourteen miles north of Klamath Falls, 

 Oregon. 



Type Material. Five specimens, of which one is designated as holotype 

 and the four others as paratypes, are deposited in the United States 

 National Museum, Accession no. 531029. The holotype is shown on plate 

 123 as fig. 2; two paratypes on the same plate as figs. 3 and 4. A series 

 of specimens from the same locality, collected by Mrs. L. Sinitsin, are 

 accessioned in the United States National Museum, no. 531064. The indi- 

 viduals of this last named series are designated as locotypes of the new 

 variety. 



Parapholyx kla))iathensis sinitsini is a form smaller than the tyjucal 

 klamathensis. The two forms have the same columella and angular base 

 of aperture. The new variety has a higher spire than the typical form and 

 the shell is more globose. Some individuals wdth diagonal ridges resemble 

 diagonalis from Crater Lake but in that form the columella is wider, more 

 concave and flatter and the aperture is more effuse. The spire of the new 

 variety varies from flat to elevated depending upon the deflection of the 

 aperture. Sinitsini has about the same size as Parapholyx solida optima 

 but that form has a flat spire and a different aperture, especially in the 

 region of the columella. 



This variety is named for Mrs. L. Sinitsin. 



