Length 3.1, diam. 1.9, length aperture 1.1 mm.; 5 whorls (type). Length 2.8, diam. 1.6, length aperture 0.85 mm. Operculum having the spiral rather large, the nucleus being above the lower third. This little species resembles _Lyogyrus_ by its tubular whorls of small calibre. The whorls are more convex and increase less rapidly than in _Amnicola walkeriana_, which is also less slender. _A. schrockingeri_ Ffld. has less deeply convex whorls, and the apex is more acute. _A. bakeriana_ is much larger, with a more obtuse apex. Found in Short Point Bay, Oneida Lake, near shore, in 3 feet of water, bottom of sand with algae; also in Lower South Bay, etc. Collected by Mr. F. C. Baker. It is named for Dr. John M. Clarke, the distinguished Director of the Museum of the State of New York. AMNICOLA ONEIDA, n. sp. The shell is typically more slender than _A. lustrica_, turrited-conic, narrowly umbilicate, corneous, minutely striate. The apex is slightly obtuse, but the first whorl projects visibly, as in _lustrica_, whorls _very convex_, parted by a _deep suture_. The aperture is ovate, small, its length contained more than 3 times in that of the shell; upper extremity narrowly rounded. The peristome is continuous, thin, very briefly in contact with the preceding whorl above. Length 4, diam. 2, length of aperture 1.25 mm.; 6 whorls. Lower South Bay, Oneida Lake, N. Y., collected by F. C. Baker, 1916. This species is typically narrower than _A. lustrica_ Pils., with a smaller aperture and shorter whorls; but it is chiefly distinguished by the more convex whorls (deeper suture), and the rounded instead of angular posterior end of the aperture. In _Paludestrina nickliniana_ the last whorl is much longer. Possibly it may be a subspecies of _lustrica_, yet it has so distinct an appearance that a special name seems desirable. There are also wider examples, which still differ from _lustrica_ by the deeper suture and aperture. NEW GENERA AND SPECIES OF CENTRAL AMERICAN NAIADES. BY L. S. FRIERSON. In 1893 Messrs Crosse and Fischer divided the Mexican Naiades into quite a number of sections, to which they assigned names. Almost simultaneously (in 1900) von Martens and C. T. Simpson, in treating the Central American Naiades, accepted some of these sections of Crosse and Fischer, raising them to generic or subgeneric rank. Because of paucity of material, considerable diversity of opinion concerning the specific identity of several species may be noted in the works of these authors. Furthermore, their work of classification being done independently and from different points of view, the same species was sometimes placed by them in different genera. Thanks to the arduous labors of A. A. Hinkley, who has again and again enriched our cabinets with material and data from these tropical countries, we are enabled to offer the following suggestions concerning some of the genera of these shells, and also the description of an unpublished species.