ASTARTIDA. ba 
Shell suborbicular, compressed, thick, smooth or concentrically 
furrowed ; lunule impressed ; ligament external ; epidermis dark ; 
hinge-teeth 2-2, the anterior tooth of the right valve large and 
thick; anterior pedal sear distinct; pallial line simple. 
Animal with mantle open; margins plain or slightly fringed ; 
siphonal orifices simple; foot moderate, tongue-shaped ; lips 
large, palpi lanceolate; gills nearly equal, united behind, and 
attached to the siphonal band. 
The animal of Astarte borealis has mantle-margins free, plain, 
slightly cirrated in the branchial region; united posteriorly by 
the branchial septum, forming a single excurrent orifice; pedal 
muscles distinct from adductors ; gills flat, finely striated, desti- 
tute of internal partitions; outer gill narrow, elliptical, with a 
simple margin; inner gill grooved, conducting to the mouth. 
ASTARTELLA, Hall and Whitney, 1858. The anterior tooth of 
the right valve has a longitudinal pit in the summit. A. vera, 
Hall (exxii, 14,15). Coal-measures ; Illinois and Indiana. “* “ 
GONILTA, Stol., 1870. Shell orbicular, small, hinge with three 
distinct cardinal teeth in each valve, surface with angular strie, 
no epidermis. A. bipartita, Philippi ,(exxii, 35). The round, 
rather Lucinoid form and the angular striation of the surface 
indicate in this species a distinct section of Astarte, similar 
to Cyclas, a subgenus of Lucina. 
LrRopIscus, Con., 1869. Shell subquadrangular, concentrically 
ribbed, posterior side lobed by an impressed line; hinge with 
two cardinal teeth in each valve, right valve with a small pyram- 
idal anterior lateral tooth, left with a posterior one distant 
from the cardinals. Ast. tellinoides, Con. Eocene. 
RIcTOCYMA, Dall, 1871. Shell and hinge like Astarte ; sculpture 
consisting of broken, nodulous waves, irregularly concentric, 
covered witha thick epidermis ; equivalve and nearly equilateral. 
A. mirabilis, Dall (exxii, 36). Alaska. 
CRASSINELLA, Bayle. Shell obliquely lengthened, subquadran- 
gular. A. obliqua, Desh. Jurassic. 
PLIONEMA, Conrad, 1872. Shell subrotund, sculptured, with 
close radiating lines or fine ribs; hinge of left valve with two 
robust diverging teeth; lunule none, A. Guerangeri, d’Orb. 
GooDALLtA | Turton, 1822), Deshayes, 1860. 
Syn.—Parastarte, Conrad, 1862. Callicistronia, Dall, 1883. 
Distr.—Recent; Europe, U. 8. Fossil, 8 sp. Eocene; Paris. 
G. miliaris, Defrance (exxi, 18). 
Shell small, trigonal, equivalve, inequilateral ; valves closed ; 
cardinal teeth in the right valve two, diverging, separated by a 
triangular socket; in the left valve, one triangular, sometimes 
bifid ; lateral wanting, or rudimentary ; ligament external, very 
short; pallial line simple. 
