372 Binney's Monograph of the Helices 
ment of the whorls is the same, and the size cor- - 
responds; but the epidermis is much more yellow, 
and the delicate and beautiful oblique striz of that 
species are replaced by rough corrugations. The 
body-whorl is also decidedly larger and more volu- 
minous. On the lower surface, the resemblance dis- 
appears; the umbilicus being open and deep, the lip 
much less reflected and not flattened, and the aper- 
ture more roundéd. The greater capacity of the 
body-whorl is also more apparent on the base. 
It is named after Dr. Townsend, who sicco MEE y 
Mr. Nuttall in his expedition to Oregon. 
20. HELIX CONCAVA. 
Plate XIV. 
H. testà planulata, latè umbilicatà, albido-corneà ; énfiictibos quinis 
ad basim rotundatis ; apertura sub-rotundatà, superné depressá ; oae 
subtus reflexo, supra simplici ; columella brevi, callosà. 
Synonyms AND REFERENCES. E 
Helix c cóncava, . Say.. Journ. A. N. S. Phila, ti. 
159. 
Helix planiicbáides, FORMAM ; Prodr., No. p 
Pl. uxxxu., fig. 4. | 
Helix YeiicótVolülisn, Lea. Trans. Am. Phil. I2 
ERST! Pl xxm, fe: 72... 
Mesomphix planorbéides, Rafinesque. : 
Description. 
Animal. Upper surface greyish, idus e 
base dirty-white, collar reddish-orange, posterior ex- 
