280 AVICULIDA. 
Horvesia, Laube, 1866. 
Etym.—Dedicated to Dr. Moritz Hornes. 
Syn.—Goniodus, Dunker. 
Obliquely elongated, solid, inequivalve, left valve inflated, 
with incurved beak, right more or less flattened, hinge-line 
straight, with a short, narrow, somewhat contorted anterior and 
a long posterior wing, not separated from the body of the shell, 
except by a shallow marginal insinuatior ; ligament situated i in 
several pits externally on the hinge-line, one pit being below the 
beak and reaching rather internally, one is on the anterior and 
the remainder on the posterior side; hinge in the left valve con- 
sisting of a strong oblique tooth under the beak, separated by a 
pit from a smaller anterior cardinal; in the right valve there is 
only one strong tooth, besides that there are generally numerous 
crenulations at the margin of the hinge-line in both valves, and 
one or two oblique submar ginal ribs posteriorly ; ; muscular scars 
two, deep, close together, not far from the umbones. Several of 
the Triassic species of Gervillia, most likely, are referable to 
this group. 
Ditters from the typical Gervilliz by the peculiar structure of 
the hinge, and by a more or less lengthened septum going 
through the cavity of the umbones. 
ACTINODESMA, Sandberger, 1856. 
Distr.—A. malleiforme, Sandb. Devonian; Germany. 
Slightly obliquely and broadly oval, moderately convex, with 
a long, straight hinge-line, produced on either side into a narrow 
wing, hinge with a number of ribs inclined towards the horizontal 
hinge- line on either side of the central area on which they are 
absent; these ribs are separated by grooves in which the liga- 
ment is said to be lodged, being almost quite internal. 
Stoliezka says: “I ‘do not think that it has been sufficiently 
established that the grooves alluded to are really ligament or 
cartilage-crooves. They rather appear to me to be identical 
with similar hinge-ribs of Pterinea and Gervillia, and the liga- 
ment may have been external and marginal, attached to the 
thickened margin of the shell which slopes internally, as is, for 
instance, the case in BIgeo species of Avicula and particularly in 
the Meleagrina group.” 
SupramMity VULSELLINA. 
Ligament lodged in a special single groove or pit, extending 
from the beak internally. 
VULSELLA, Lam., 1799. 
Syn.—Reniella, Swainson, 1840. 
Distr.—i sp. Red Sea, India, Australia, Tasmania. Fossil, 
Tsp. Eocene—; Britain, France. V. rugosa, Lam. (cxxxi, 66). 
