Cerion portillonis Welch, 1934
"The shell is similar to Cerion ramsdeni differing from it in size, being constantly smaller. The ribs are more closely set and more evenly spaced. The color is white but specimens may be marked splotches of army brown but this is fairly rare. Length 19.4 mm., diam. 9.7 mm. Paratypes (b-d) measure from 15 x 8.4 mm. to 21 x 10 mm.
The locality is along the shore road about 10 kilometers east of Ensenada de Mora, near Portillo, Oriente province.
They were found in great abundance, about a dozen to the square foot, on grass and trees. Collected by Pilsbry and Welch, August 11, 1928. Specimens collected by us from Aguada, 4 kilometers east of Ensenada de Mora, on August 11, 1928, are intermediate between C. r. portillonis and C. ramsdeni. They were also abundant, about a dozen to the square meter. They measure from 20 x 9.5 mm. to 22.8 x 10.8 mm. (Pl. 11, figs. 2 e, f.)"