40 DESCRIPTION OF FIFTY-TWO SPECIES OF TJNIONIDiE. 



defined and on this specimen are five in number. It belongs to the group of 

 JRaleighensis (nobis), and may be placed between that species and Ahbemllensis. It 

 is larger than the latter and is higher in the wing than either. The beaks of all 

 the specimens were too much eroded to give the character of the undulations of 

 the tips. 



Unio insolidus. pi. 13, fig. 37. 



Testa Ifevi, oblonga, parum compressa, ad latere parum planulata, insequilaterali, postice obtuse bian- 

 gulari, antice rotundata ; valvulis subtenuibus, antice parum crassioribus ; natibus subprominent- 

 ibus, ad apices undulatis; epidermide pallido-viridi, obsolete radiata; dentibus cardinalibus parvis, 

 compressis ; lateralibus longis, lamellatis rectisque ; margarita alba et iridescente. 

 Shell smooth, oblong, somewhat compressed, slightly flattened at the sides, ine- 

 quilateral, obtusely biangular behind, rounded before ; valves rather thin, rather 

 thicker before ; beaks somewhat prominent, undulate at the tips; epidermis pale 

 green, obscurely radiate; cardinal teeth small, compressed; lateral teeth long, 

 lamellar and straight; nacre white and iridescent. 

 Proc. Acad. Nat. Sci., 1812, p. 159. 

 ffaft.— Abbeville Dist., So. Car., Dr. Barratt; Fredericksburg, Va., Dr. Emmons; 

 Irwin's Creek, Mecklenberg Co., North Carolina, C. M. Wheatley. 



My cabinet and cabinet of C. M. Wheatley. 

 Diam. -7, Length 1-3, Breadth 2-3 inches. 



Shell smooth, oblong, somewhat compressed, slightly flattened on the sides, ine- 

 quilateral, obtusely biangular behind, rounded before; substance of the shell rather 

 thin, thicker before ; beaks somewhat prominent, undulate at the tips ; ligament 

 long, thin and light brown; epidermis pale green, obscurely radiate and with rather 

 distant marks of growth; umbonial slope rounded; posterior slope carinate, narrow- 

 elliptical, almost winged, with two green lines from the beaks to the margin ; car- 

 dinal teeth small and compressed; lateral teeth long, lamellar and straight; anterior 

 cicatrices confluent, rather large and very slightly impressed ; posterior cicatrices 

 confluent and scarcely perceptible ; dorsal cicatrices placed above the centre of the 

 cavity of the beaks ; cavity of the shell shallow and wide; cavity of the beaks shal- 

 low and obtusely angular; nacre white and iridescent. 



Remarks. — I have had three specimens of this shell many years from Dr. Bar- 

 ratt of Abbeville District, S. C. This species is so near to U. decoratus (nobis) in 

 many characters, that I thought it might be merely a well-marked variety of 

 that species. Having about thirty specimens from Mr. Wheatley taken in a more 

 northern habitat of a different State, I do not hesitate to consider it distinct. It 

 difters from decoratus in being more oblong and in having rather larger teeth. 



