6 
by the two sides of the spire in univalves. This angle, combined 
with the length and breadth of the shell, and proportionate length 
of the mouth, would, it is conceived, give us a better idea of form 
than we can have by the present mode of description. It is a plan 
we have adopted in describing our marine shells. 
3. H. TRiDENTATA. — Shell depressed, spire very little raised, 
brownish or horn color ; whorls five, crossed by numerous raised, 
equidistant, acute lines, separated by regular grooves ; aperture 
lunate, three toothed ; teeth placed triangularly, one on the pillar 
lip situated diagonally ; outer lip abruptly contracting the aper- 
ture, widely reflected and white, furnished with two of the teeth 
resembling projecting angles. Umbilicus moderate. 
Half an inch wide. Inhabits the Middle States. Plate 2, fig. 1. 
Cochlea parva, umbilicata, tenuiter striata. Tridens sc. in 
triangulo positi, nempe unus ad fundum oris, alter ad columellam, 
tertius ad labrum. Lister, Conch, tab. 92, fig. 92. 
The three curves formed by the two teeth in the outer lip of 
this shell bear considerable resemblance to the ornament often 
placed upon panels in Gothic architecture. It is found under the 
loose moist bark of decaying trees in some plenty. Belongs to the 
genus Polydontes, Montf. 
As many of the compound terms as possible ought to be ban- 
ished from the language of Natural History, we would therefore 
propose that the term outer-\i^ and pillar-Y\^ be substituted by 
Labrum and Labium; these would be equally expressive, and 
occupy less space in a description. 
4. H. ALTERNATA. — Shell somewhat convex, fuscous, varied or 
alternating with pale raj's ; whorls five, striated across with raised 
equidistant acute lines, forming grooves between them. Aper- 
ture thin and brittle ; lip regularly curved, within glossed with 
perlaceous, and when placed before the light, the fuscous lines 
appear sanguineous. Umbilicus large, exhibiting all the volutions. 
Three-fourths of an inch wide. Inhabits the Middle States. 
Plate 1, fig. 2. 
H. radiata, Gmelin’s Ed. of Syst. Nat. p. 3634. 
Cochlea umbilicata, fusca, sive variegata, capillaribus stryis 
leviter exasperata. List. Conch, tab. 70, fig. 69. 
Lister’s figure, which is, without doubt, a representation of this 
species, is referred to in Gmelin as H. Radiata, but we believe 
