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 distinct. 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 If in., length 1 in., diam. I 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, scutum well 



