302 PROCEEDINGS OP THE NATIONAL MUSEUM. vol. 5S, 



All the specimens of Spliaeromelama figured on plate 17 are sup- 

 posed to be mutations of this species. Figure 11 represents one ex- 

 treme, in which the shell is larger, more slender, and of thinner tex- 

 ture, while figure 10 represents the other extreme, with short, stout 

 chunky form. vSeveral of the specimens have a faint, broad band of 

 darker color encircling the middle portion of the whorls. 



It is a pleasure to name this species in honor of Mr. Hinkley, whose 

 explorations in Mexico and Central America have done much toward 

 increasing our knowledge of the Molluscan fauna of those regions. 



COCHUOPA DULCENSIS, new species. 



Plate 17, figs. 1-3. 



Shell valvatiform, depressly, conically turrited. Whorls three and 

 a half, excavately shouldered. Spirally ribbed with seven strong, 

 nearly equal ribs. The first rib is at the shoulder, the third is at the 

 periphery, the seventh marks the circumference of the umbilicus. 

 Near the aperture the last whorl descends from the second to the 

 third rib. Color, greenish horn; ribs reddish chestnut, showing as 

 spiral bands within the aperture. Aperture entire, slightly oblique, 

 subcircular, slightly narrowed at the upper part. Outer lip simple, 

 minutely angled at each rib; columellar lip somewhat expanded and 

 a little thickened within. Principal growth lines well marked on the 

 shoulder, between the ribs and on the base, radiating, set at regular 

 intervals and showing hints of chestnut coloring. Minor growth 

 markings numerous, fine. Umbilicus wide, perspective, somewhat 

 funnel-shaped, showing all the whorls, which appear to be loosely 

 coiled. Operculum corneous, paucispiral, pale yellowish. 



The tj-pe. Cat. No. 336413, U.S.N.M., measures— altitude, 1.3 mm.; 

 greatest diameter, 3 mm.; least diameter, 2.3 mm. It and nine 

 other specimens were presented by Mr. Anson A. Hinkle^^, who col- 

 lected them in January, 1917, in the Dulce River, Guatemala. 



The general aspect of this species resembles that of the well-known 

 Valvata tricatinata. Viewed from above the two species are almost 

 exact counterparts of each other so far as form and sculpture are 

 concerned. In the living specimens the chestnut coloring of the 

 spiral ribs does not show well against the dull background of the gen- 

 eral surface, but in the dead shells the general color bleaches to a 

 3^ellowish tinge and the dark coloring of the ribs becomes one of the 

 most prominent features of the shell and throws the ribs into sharp 

 relief. Within the aperture the chestnut banding is prominent in 

 living shells, but hardly apparent in the dead specimens. The species 

 is perhaps the most attractive of the Cocliliopas thus far discovered 

 in Central America. The spiral ribs are subject to some variation in 

 number and strength. 



