44 THE NAUTILUS. 



extends into Canada and as far west as the Rocky Mountains, but 

 not south of the Ohio and Missouri rivers. 



Physa warreniana Lea, is a lees inflated form and may be ranked 

 as a variety. 

 Physa lordi Baird. 



This species was described in 1863 from specimens taken in Oso- 

 yoos Lake, British Columbia. It is a northwestern species, and 

 probably does not extend east much beyond the Rocky Mountains. 

 It is the largest American species of the genus, and may be readily 

 distinguished by its large size, inflated, gibbous form, and thin and 

 fragile shell. 

 Physa parkeri Currier. 



The consensus of opinion places this shell with P. lordi Baird as a 

 variety, but in this opinion I do not concur. I am unable to see any 

 similarity in the two forms except in size, and the general outline of 

 the form when P: parkeri is not shouldered. P. lordi is a large gib- 

 bous form, while P. parkeri is large and square shouldered. It is 

 also a thick, heavy shell of a different color and structure. I leave 

 the ma.tt.er to be determined by those more familiar with these forms 

 than I am. 



Distribution, Northern Michigan. 

 Physa rhomboidea, n. sp. PI. II, fig. 6, 7. 



Shell rhomboid-ovate, large, heavy, robust, yellowish horn-color to 

 pale yellowish-brown, texture fine, surface undulating and shining 

 when not covered with a dark coating, spire elevated, acute with 

 dark brown tip, whorls five convex, sutures much impressed, aperture 

 ovate, lip simple, not expanded, sometimes a little compressed, thick- 

 ened on inner margin with reddish-brown callus, columella well cov- 

 ered with heavy deposit continuing and extending from the lip. On 

 many of them the columella is folded so as to form a narrow um- 

 bilicus. 



Length 16 mm. diameter 9 mm. Bi-annuan. 



This shell was collected by me in Cedar and Muddy creeks, near 

 Sedalia, Mo. I have since found it at Dardanelles and Sulphur 

 Springs, Ark., and at three localities near Las Vegas, New Mexico. 

 I have sent to Prof. Pilsbry examples from Missouri and Las Vegas. 

 In a reservoir on Romaro ranch I found some dead shells consider- 

 ably larger than the one described. 



It is distinguished by its robust appearance, deep sutures, con- 



