112 THE NAUTILUS. 
two or three distant growth lines. Beaks prominent and surrounded 
by four or five coarse, sharp, widely separated irregular undulations. 
Ligament reddish, short, thin and scarcely elevated above the dor- 
sum. Dorsal margin slightly elevated ; anterior margin gracefully 
rounded, base uniformly and slightly curved; posterior margin 
pointed. Posterior area abrupt with two slightly raised lines formed 
of irregular elevations from beak to margin. Umbos gracefully and 
uniformly rounded; greatest diameter in the centre of the disk. 
Nacre sky-blue throughout, sometimes darker within the pallial 
line. Beak cavities slight and abrupt. Cicatrices well impressed, 
smooth and distinet. Cardinals solid, prominent, double in the left 
valve and single in the right valve, laterals double in the left valve 
and disposed to be double or tripartite in the right valve and joined 
to the posterior cardinal by a distinct elevation of the dorsal plate. 
Width 1% in., length 1 in., diam. ¢ in. 
Habitat: Ocklocknee River, Leon County, Florida. 
Type in National Museum. 
Remarks:—This anomalous little shell was taken with U. klein- 
ianus Lea, lienosus Con., kirklandianus Wright and floridensis Lea. 
It does not seem to group well with any known species, though the 
the beak sculpture indicates a relationship with U. forbesianus Lea. 
In some respects it reminds one of U. macrodon Lea, but it is more . 
inflated, not as solid usually, darker in epidermis, rayless, with deeper 
beak and shell cavities. The lateral teeth are longer, higher and 
end more abruptly, besides being double or tripartite in the right 
valve. The very young show slight traces of broad, distant rays. 
It certainly groups with U. forbesianus Lea, but is easily distin- 
guished from the young of that species by its want of rays, lighter 
epidermis, rounded base, rounded umbonal angle, flattened umbos 
and it is smoother on the posterior area. 
NEW PISIDIA. 
BY DR. V. STERKI. 
Pis. singleyi n. sp. 
Mussel small, rather high, somewhat oblique, ventricose, beaks 
prominent, also in the young, rounded but narrow on top, slightly 
posterior, vertical section broadly heart-shaped; superior margin 
moderately curved, rather short, scutellum slightly, seutum well 
