NO. 1587. ON PLANORBIS MAGNIFICUS—BARTSCH. 699 



born during my absence, and these, like well-behaved Planorhis^ have 

 small but well-defined eyes on the inner side, at the base of the 

 tentacles. 



Figures 7, 8, and represent three views, profile, bottom and top, 

 of the largest specimen, all natural size. This shell (Cat. No. 

 103321, U.S.N.M.) measures: Greatest diameter, 37 mm.; lesser 

 diameter, 2G mm. ; altitude, 25 mm., and is the largest specimen on 

 record up to date. 



PLANORBIS EUCOSMIUS, new species. 

 IMiite LVII, tiys. 1-3. 



Shell resembling Planorhis hicarinatus Say in outline but much 

 smaller than that species, of yellowish horn color with two rather 

 broad, briglit chestnut bands. 



Shell biconcave. Entire surface marked by very strong lines of 

 growth and numerous fine spiral lirations. Upper surface strongly 

 umbilicated, showing a little more than three and one-half whorls. 

 A moderately strong carina is situated about halfway between the 

 periphery and the suture. The upper surface is nuirked b}^ the two 

 chestnut bands which are of about equal width, a little more than one- 

 third as wide as the space between the dorsal carina and the suture. 

 The posterior of these bands is a little nearer the suture than the 

 carina, and the anterior one is about as far anterior to the carina 

 as the other is posterior to it. Periphery well rounded. Base 

 broadly umbilicated, showing a little more than three and one-half 

 turns. Outer limiting angle of the umbilicus marked by an obtuse 

 carina. Aperture decidedly oblique, with somewhat expanded, l)lack 

 edged peristome; slightly angulated at the posterior carina and more 

 strongly so at the basal one ; outer lip reenf orced within by a moder- 

 ately thick white callus. Parietal wall covered with a thin callus. 



The type (Cat. No. 193890«, U.S.N.M.) measures: Greater diam- 

 eter, 6.6 mm.; lesser diameter, 5.1 mm.; altitude, 3.1 mm. 



The type and 46 specimens (Cat. No. 193800. U.S.N.INI.) were col- 

 lected by the author in Greenfield Pond, near Wilmington, North 

 Carolina. 



PLANORBIS EUCOSMIUS VAUGHANI, new subspecies. 



Plate LVII, fijis. 4-G. 



Similar to Planorhis eucosmius^ but with much narrower and deeper 

 basal umbilicus, with the basal carina much stronger and with the 

 last Avhoi'l considerably more expanded toward the aperture. The 

 spiral sculpture and the lines of growth are less strongly developed 

 than in evcosmius. The ])resent form is also considerably higher than 

 Planorhis eMcosmius. Three specimens of this subspecies (Cat. No. 



