THE NAUTILUS. 117 



THE GEOGRAPHIC DISTRIBUTION OF PLANORBIS UMBILICATELLUS. 



BY E. G. VANATTA. 



This species was first described by Mr. J. AV. Taylor in the Jour- 

 nal of Conchology, 1883-85, Vol. IV, p. 351, uuder the name P. 

 umbilicatus; but since Miiller had previously described a P. tanbili- 

 catus in 1774, Cockerell renamed Taylor's shell P. umbilicatellus in 

 the Conchologist's Exchange, November, 1887, p. 68. 



It is now known from the following localities : 



Manitoba : Brandon and Birtle, R. M. Christy ! Original locality. 



Minnesota: Dallas Lake, Wright Co. II. E. Sargent! Coll. A. X. S. i'. 



St. Michael's, H. E. Sargent! Coll. A. N. S. IV 



Iowa: Near Davenport, H. A. Pilsbry ! Coll. A. X. S. P. 



Montana: Mingusville, H. Squyer ! Naut. VIII, p. 65. 



Colorado : Davidson's Ranch, Boulder Co., J. D. Putnam ! Coll. A. N. S. P. 



From these localities it seems to have a wide range through the 

 northwestern States, the extreme points being Birtle, Manitoba ; 

 Mingusville, Montana; Davenport, Iowa, and Boulder Co., Col- 

 orado. 



The shell is grayish-white, with a flat spire and a deep umbilicus. 

 It may be easily distinguished from P.parvus Say by its deeper and 

 narrower umbilicus and fewer whorls, and from P. deflectus Say by 

 the flat spire, lack of blunt keel at periphery and the heart-shape of 

 the aperture ; deflectus having a rounded aperture. 



No doubt this species will be found well represented in the col- 

 lections of many western conchologists, unidentified or under the 

 name " deflectus." 



TRANSACTIONS OF THE ISAAC LEA CHAPTER. 



[Conducted in the interest of the Isaac Lea Conehological Chapter of the Agassiz Associa- 

 tion by its General Secretary, Mrs. M. Burton Williamson.] 



The annual election for officers occurs on the last Wednesday in 

 December, and as Christmas for 1895 occurred on the same day, our 

 election was postponed for one day. All the members of our Chap- 

 ter residing in California were invited to be present at the home of 

 the General Secretary on Thursday, December 26, to elect officers, 

 as provided for in Article V of our Constitution. As our Pre-ident, 

 Professor Keep, lives five hundred miles from Los Angeles, he was 



