CHIEFLY OF THE UNITED STATES. 18a 



with which I am acquainted. The four specimens before me — two being young with 

 unfinished lip — are rather smaller than that species, and are of a darker horn-color. 

 The superior portion is more rounded and the oblique striae are not decussate, as in 

 Pennsi/lvamca. It also has a single rather large curved tooth on the columella, 

 which Prof, Green's species has not. It has the outer lip more flattened, and the 

 callus on the inferior portion of the lip is more developed and differently formed, 

 being more like that o^ palUata, Say. The young specimens are somewhat carinate 

 on the middle of the whorl, and the striae are here slightly deflected and diminished 

 in size. Neither of the specimens were alive when they reached me, so that a de- 

 scription of the soft parts cannot be now given. I owe the possession of two speci- 

 mens to the kindness of Mr. Clark. He received them from Professor Christy, who, 

 while pursuing his geological researches, does not neglect to observe the Mollusca of 

 our country. 



Helix (Poltgtra) Couchiana. PI. 24, fig. 112. 



Testa superne paulisper elevata, subplanulata, inferne subinflata, nitida, albida, longitudinaliter et subtiliter 

 striata, minute perforata ; anfractibus quinis ; apertura rotundata, quinquidentata ; labro subacuto. 



Shell slightly raised above, flattish, somewhat inflated below, shining, whitish, 

 longitudinally and finely striate, slightly perforate ; whorls five ; aperture rounded, 

 five-toothed ; lip subacute. 



Proc. Acad. Nat Sci. 18.57, p. 102. 



Hah. — Taraaulipas, Mexico, Dr. Berlandier. 



My cabinet and cabinet of the Smithsonian Institution. 

 Diam. -41, Length -15 inch. 



Remarlcs. — This was among the shells brought by Lieut. N. D. Couch, U. S. A., 

 from Tamaulipas, being part of Berlandier's collection purchased by Lieut. Couch, 

 and presented to the Smithsonian Institution. It cannot be confounded with 

 Troostiana or Tamaulipasensis, though belonging to the same natural group. The 

 four teeth are so placed that each succeeding one becomes more transverse. The 

 umbilicus is remarkable ; at the last whorl it is suddenly enlarged by the curve of the 

 whorl changing. I name it after Lieut. Couch, who so liberally presented Dr. Berlan- 

 dier's collection to the Smithsonian Institution. 



Helix (Poltgyra) Tamaulipasensis. PI. 24, fig. 113. 



Testa superne paulisper elevata, subplanulata, inferne subinflata, nitida, albida, longitudinaliter et 

 subtiliter striata, minute perforata; anfractibus quinis; apertura lunata, tridentata; labro spissato, 

 reflexo. 



Shell slightly raised above, flattish, somewhat inflated below, shining, whitish. 



