268 Description of some new Shells. 
the spark. When the battery circuit is complete through the in- 
strument, the end 0, of the armature is raised by the magnet, the 
connexion is broken at ¢, and the end 9, falls by its weight, again 
rises, thus giving a rapid succession of sparks at c.. The extrem- 
ities-of the armature are wound with a little sewing silk, or thread, 
to prevent their retention by the magnet. 
Washington, November 13th, 1838. 
Arr. VI.—Description of some new Shells ; by SERIA Tappan, 
Steubenville, Ohio. 
Pror. Keccining —I send for publication in the Journal of Sci- 
ence the following descriptions of some shells found in Ohio, 
which are believed to be new. 
“Unio Sayn, ‘Ward. Plate IIL. Fig. " 
Shell - sub-rhomboidal, inequilateral, transverse, compressed ; 
valves thin, beaks slightly prominent and divergingly wrinkled ; 
cardinal teeth oblique, single in the right and double in _ left 
valve ; lateral teeth slightly curved ; nacre ‘white. 
Hab. Walnut creek and Ohio patie, near Circleville. W. H. 
Price. My cabinet ; cabinets of Dr. Kirtland, R. Buchannan, 
Esq., B. Tappan, A. Binney, Esq. Dr. Gould, Dr. Jay, Col. Tot- 
ten, d&oc., &c. 
Diam. 1. Length 1.60. Breadth 2.80. =f 
Shell inequilateral, transverse, sub-rhomboidal, compressed ; 
posterior and superior margins wectilinees). basal margin curved, 
anterior margin regularly rounded. Valves thin, translucent. 
Beaks slightly prominent, incurved and divergingly wrinkled, 
placed near the anterior margin., Umbonal slope sub-carinate, 
carina somewhat elevated. Ligament long, narrow, nearly straight 
and partially concealed. Epidermis-pale yellow, inclining to cu- 
preous on the umbos; glabrous, with indistinct capillary rays of 
a lighter color extending over the whole disk ; lines of growth 
black, and very distinct ; two faintly imapeniene lines diverging 
from under the points of ie beaks and extending to the posterior 
Basal margin. Cardinal teeth very oblique, not prominent, single 
in the right and double in the left valve, slightly crenate ; lateral 
teeth lamellar, one curved. Anterior cicatrices distinct, poste- 
