THE NAUTILUS. I <> 



The Sycnti/pits group probably originated, as Mr. Grabau suggests, 

 with such forms as F. bnriisii, perizGnutttin and tainpaensis in tlie 

 Upper Oligocene (Lower Miocene?) and F. coronulum and nujosum 

 in the Middle Miocene. It ^eems ratlier a doubtful conclusion to 

 refer to F. rugosum as the direct ancestor of F. canaliculatum. 

 have not seen the " Faison variety " of F. canaUferum referred to, 

 but I am inclined to consider F. alcealus and incite as intermediate 

 forms and to trace the line of ancestry of F. canaliculatum and pijrum 

 through the same formations in which I trace F. carlca and perver- 



O 



sum, viz., the Miocene of Virginia and North Carolina and the Plio- 

 cene of the Waccamaw and Caloosahatchie. 



The typical F. incite of Yorktown seems to have evolved into two 

 forms in the Duplin county beds ; the one, F. conradil 1 Tuomey and 

 Holmes, leads to the so-called canaUferum Conr., the type of which 

 is the F. canaliculatum T. & H., from the Waccamau, and in no way 

 separable from the recent form. The other form, derived from indie, 

 represents a very mutable species, and to the various forms had been 

 applied the names of F. carolinensis, excavatus, elongatus and pyri- 

 formis. These exhibit, however, all gradations and extend through 

 the Pliocene to the recent F. pi/rum Dillvv. 



F. conclnnum does not belong to the " Middle Miocene." The 

 type locality is Sampson Co., N. C., and I found it also along the 

 Cape Fear River, ten miles above Elizabeth town, Bladen Co., in a 

 bed typically Duplin. I do not know the forms which Conrad de- 

 scribed as amcenum and Kerrii and a study of the form from Walker's 

 Bluff, N. C., might throw additional light on the subject. 



THE GREATEST AMERICAN PLANORBIS. 



BY HENRY A. PILSBRY. 



Planorbis magnificus n. sp. 



The shell is very large and high, sinistral as usual, the upper or 

 spire half yellow or pale brown, the lower or umbilical half dark 

 brown. Surface glossy, finely marked with growth-lines, and usually 

 some spiral series of minute long granules, as in many species of pond 



That F. conradii represents an intermediate form between incile and canali- 

 culatum is clearly shown by a series in the Joseph Willcox collection of Ful- 

 gurs, presented to the Academy of Natural Sciences, Philadelphia. 



