THE NAUTILUS. 127 



pyramid in otliers, and is considerably longer tlian the aperture ; the 

 aperture is roundly elliptical and almost continuous, differing mark- 

 edly in this respect from humilis ; the inner lip is more erect in the 

 present S[)ecies, which causes the umbilicus to be round, deep and 

 open. The umbilical region is gracefully rounded. Typical ex- 

 amples measure as follows : 



liHiigth 6.00; width 3.00; aperture length 3.00; width 1.7.') mill. 

 (Indiana.) 



Length G.OO; width 3.00; aperture length 2. .50; width 1.2o niill. 

 (Penn.) 



Length .5. .50; width 3.00; a|)ertiire lenirth 2.7.5; width L.5() mill. 

 (Ills.) 



This species is widely distributed, being found from IVIaine to Cali- 

 fornia and from Canada to Mexico. 



Lymticp.a desidiusa Say var. modi cello Say. 



Lyinaeus modicellns Say, Join-. Phil. Acad., V, p. 122, 1825. 



Say described this s|)ecies froni two S|)eciinens which are still pre- 

 served in the Pliiladelphia Academy. It would seem to be distinct 

 enough to be recognized at least as a variety of desidiosa, to which 

 it is more closely allied t\ii\u io humilis. The |)rinciple characteris- 

 tics are the short, dome-shaped s])ire, the regtdar elongate-ovate aper- 

 ture and the large size of thi' last wh(irl as compared with the spire. 

 The umbilical chink is narrowly open and there is a small plait on 

 the colum.ella. Typical specimens measure as follows: 



Length 8.50; width 4.7.5; aperture length 4.7.5; width 2.75 mill. 

 (Say's type.) 



Length 7.7.5; width 3.25; aperture length 4.50; width 2.25 mill. 

 (Berry Lake.) 



Length 7.00; width 3.50; a|)erture length 4.50; width 2.00 mill. 

 (Berry Lake.) 



The range of this form, as far as known, is from Ontario to Oregon 

 and south to Texas. It has been found in Big Payette Lake, Idaho, 

 at an altitude of 5,000 feet above the sea level. 



The forms described by Dr. Lea as L. plica, plaiudata, exigua and 

 ruslica seem to be absolute synonyms of desidiosa, some of these 

 beinL»^, in all probability, immature forms. The types of exigua and 

 rus'icu are not in existence, so far as known. They are not in the 

 Philadelphia Academy nor in the Smitiisonian Institution. 



