170 A MANUAL OF AMERICAN LAND SHELLS. 



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MICROPHYSA. (See below.) 

 Micropliysa Ing'ersolli, Bland. 

 Shell iimbilicated, discoidal, thiu, translucid, nearly smooth, white; 

 Fig. 160. spire flat, summit subimmersed; suture impressed; whorls 

 5J, rather convex, slowly increasing, the last not descend- 

 ing, more convex below the periphery; breadth of um- 

 bilicus nearly 1"™ ; aperture subvertical, higher than 

 broad, lunate; peristome simple, acute, margins remote, 

 columellar margin slightly reflexed, basal margin subsin- 

 uate. Greater diameter 4, lesser Sf"""^; height, 2^"'"'. 



Micrnphysa Inger- /j>-\r.r,(\ \ 

 sola, enlarged. (^CiaUU.; 



Helix IngcrsoJUi, Bland, Ann. Lye. Nat. Hist, of N. Y., xi, 151, fig. (1874).— Inger- 



suLL, SjiecialEep. on Recent Moll, of Colorado, ed. 2, 397. 

 Microphysa IngcrsolH, W. G. Binney, Terr. Moll., v, 173. 



A species of the Central Province. Howardsville, Baker's Park, 

 9,300 feet above the sea ; abundant in wet places on the mountains. 

 Not uncommon at Cunningham Gulch, near the former locality, cling- 

 ing to the almost vertical face of a trachyte cliff, at an elevation of 

 about 11,000 feet; the finest specimens came from this spot. Found 

 also on the southern slope of the Saguache Mountains, in the Las 

 Animas and La Plata Valleys, in the same stations as affected by Suc- 

 cinea. All the localities mentioned are in the southwestern corner of 

 Colorado. 



This species was discovered by Mr. Ernest Ingersoll, naturalist of 

 the United States Geological Survey of the Territories, under Profes- 

 .sor Hayden. It can scarcely be compared with any known North 

 American species. 



At first sight I was disposed to consider the species a Zonites, but 

 examination of the animal proved it to belong to the Helicea. 



Jaw low, wide, slightly arcuate, ends slightly attenuated ; whole an- 

 terior surface with about 22 broad, flat, slightly separated ribs, whose 

 ends denticulate either margin. 



Lingual membrane long and narrow. Teetli about IG-l-lG. Cen- 

 trals as usual in the Helicidw (Terr. Moll., V, Plate III, Fig. V). The 

 side cusps and cutting points are wHl developed, the base of attach- 

 ment longer than wide. Laterals of same type, but asymmetrical, 

 and consequently only bicuspid. The change from laterals to mar- 

 ginals (eighth and ninth teeth of figure) is very gradual, there being 

 no splitting of the inner cutting point. Marginals (sixteenth tooth of 



