GYPIDIA. 47 
into the irregular palleal impression which unites them. Obs. 
But few species of this singular genus are known; Lamarck des- 
cribes two species from the Northern Seas. Blainville is of 
opinion that they belong to the family of Nayades. Fig. 67, 
Glycimeris Siliqua. 
GNA’THODON. Gray. (Tvabos, gnathos, jawbone; odos, odovros, 
odontos, tooth.) Fam. Mactracea, Lam. - Descr. Ovate, poste- 
riorly angulated, equivalve, thick, ventricose, inequilateral, 
covered with a greenish brown epidermis; umbo distant, pro- 
minent; hinge having in one valve, a sharp, angular, notched, 
cardinal tooth, and two lateral teeth, the posterior of which is 
elongated, and the anterior angulated, tortuous, shaped like a 
jawbone; in the other valve, two cardinal and two lateral teeth, 
the anterior of which is wedge-shaped. Ligament internal, cune- 
iform, placed in a deep cardinal pit proceeding from the um- 
bones; muscular impressions two; palleal impression having a 
slight sinus. Obs. Only one species is known, G. cuneatus, 
fig. 83, from New Orleans. It is known from all other shells by 
the characters of the hinge. 
GON'TATITES. Sow. A genus composed of species of Ammo- 
nites, Auct. in which the last whorl covers the spire and the 
sinuations of the septa are angulated. Fig. 480, G. striatus. 
GONIOSTO'MATA. Bl. A family belonging to the order 
Asiphonibranchiata, Bl. containing the genera Solarium and 
Trochus. 
GRA‘NULATED. (Granum, a grain.) Covered with minute 
grains, rough. 
GRATELOU’PIA. Moulins. Fam. Nymphacea, Lam. Deser. 
Equivalve, inequilateral, sub-cuneiform, rounded anteriorly, sub- 
rostrated posteriorly ; hinge with three cardinal teeth, a series of 
five or six irregular, small, diverging teeth behind the umbones, 
and one lateral, anterior tooth in each valve; ligament external ; 
muscular impressions two; palleal impression sinuated poste- 
riorly. Obs. This genus (Donax irregularis, Bast.) is only 
known in a fossil state. Fig. 102. G. Moulinsii. 
GRY’PHA. Lam. (From Gryps, a griffin.) Fam. Ostracea, 
Lam. Descr. Inequivalve, free; lower valve large, concave ; 
with the umbo prominent, incurved; upper valve small, fiat, 
opercular; hinge toothless, with a curved, depressed area; one 
muscular impression. Obs. These shells, which approach the 
oysters, are of a more regular form, and are remarkable for the 
curved, produced beak of the lower valve. They are only known 
in a fossil state, belonging to the more ancient strata. Fig. 182, 
Gryphea incurva. 
GYMNOLE'PAS. Bl. Orion and Cineras, Leach. 
GYPI'DIA. Dalman. A genus of Brachiopoda, thus described : 
“ Larger valve with the umbo rostrated, remote from the hinge; 
