26 THE NAUTILUS. 



records afford but little information as to whether their distribution 

 is the same or not. Taking them together, sincera is apparently a 

 northern form ranging through Canada and the northern United 

 States, from the Atlantic to the Pacific. Its range to the south 

 seems comparatively restricted, especially in the eastern states, 

 northern New York, Michigan, northern Illinois and Indiana, and 

 Nebraska being apparently the southern limit, as it is not listed from 

 Philadelphia (Shick) nor Allegheny Co., Pa. (Stupakoff), Cincin- 

 nati (Harper & Wetherby), nor Tuscarawas Co., Oliio (Sterki), nor 

 in any of the Iowa, Missouri, Arkansas or Kansas lists. I am in- 

 formed by Mr. F. C. Baker that the southern range (south to Geor- 

 gia and Louisiana) attributed to this species in his " Mollusca of the 

 Chicago Area," was a typographical error and should have been 

 placed under V. tricarinata. In the extreme west, it would seem 

 to range further south, as Dall quotes the broadly umbilicated form 

 from the San Bernardino Mountains, Cal., and Utah. Ingersoll 

 also (Rep. U. S. G. & G. Survey, 1874, p. 390) quotes sincera from 

 Colorado and Utah. The only Utah specimens I have seen, are 

 rather referable to V. humeralis Say. and it is possible that all these 

 extreme southwestern citations should be revised. 



Valvata sincera Say, PI. I, figs. 1-6. 



As Say's type of V. sincera has not been preserved, in determin- 

 ing which of the two forms, which have hitherto passed under 

 that name, is to be regarded as sincera we are necessarily re- 

 stricted to his original description and figure (a very poor one) 

 and such legitimate deductions as can be drawn from the circum- 

 stances under which his description was prepared, and his other 

 writings. When Say described his new species in 1824, the only 

 American species known to him was the typical V. tricarinata 

 and his purpose was to differentiate these two forms. Owing, no 

 doubt, to the striking and characteristic sculpture of P. tricarinata, 

 Say omitted any description of general shape. He states that P. 

 sincera is " subglobose-conic " and " very similar " to tricarinata, 

 but with a " rather larger" umbilicus. And later in describing his 

 V. humeralis, he states that it is " subglobose " and " more depressed " 

 than sincera. It hardly seems possible that Say with his remarkable 

 acumen and critical appreciation of minute differences, would have 

 failed to call attention to the depressed form and very wide umbili- 



