THE NAUTILUS. /O 



The Si/cotf/pus group probably originated, as Mr. Grabau suggests, 

 with such forms as F. bunisii, perizonatum and tamjyaensis in the 

 Upper Oligocene (Lower Miocene?) and F. coronaliiin and ruyosum 

 in the Middle Miocene. It aeeins rather a doubtful conclusion to 

 refer to F. nigosutn as the direct ancestor of F. canali cult i turn. I 

 have not seen the " Faison variety " of F. canal IJ'er urn referred to, 

 but 1 am inclined to consider F. alceai.us and incile as intermediate 

 forms and to trace the line of ancestry of jp. canalicalatnm and prjruni 

 through the same formations in which I trace F. carica and perrer- 

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

 cene of the Waccamaw and Caloos.ihatchie. 



The typical F. incile of Yorktown seems to have evolved info two 

 forms in the Du|)lin county beds; the one, F. conradii^ Tuoniey :ind 

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

 is the F. canaJicidatuni T. & II., from the Waccamau,and in no way 

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

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

 applied the names of F. carolinensis, excavatus, elonyatus and pyii- 

 formis. Tliese exhibit, iiowever, ail gradations and extend tluough 

 the Pliocene to the recent F. pi/ntm DiUw. 



F. concinnum does not belong to the " INIiddle Miocene." The 

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

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

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

 scribed as amcenuin 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 IIENUY A. I'lLSBKT. 



Planorhis magnijicus n. sp. 



The shell is very large and high, sinistral as usual, the upjier 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 interm*>diate 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. 



