108 GLOSSARY. 
Phalanges (Gr. phalans, a line of soldiers).—A term 
applied to the bones of the digits, they being 
arranged in rows. (Singular phalanx.) 
Pisiform (L. pzsum, a pea; forma, shape)—A name 
applied to the small bone of the Mammalia, 
situated in the tendon of the flexor muscle of 
the wrist, on the ulna side. It is supposed 
by some anatomists to be the remains of a 
seventh digit. 
Planiform (L. A/anum, a level place ; forma, shape).— 
Applied to a class of joints in which the 
surfaces are nearly flat ; also termed arthro- 
dial. 
Plastron (Gr. emplastron, a plaster)—The ventral 
exoskeleton of the Chelonia. 
Pleurapophysis (Gr. plewron, a rib; apophuo, | grow 
from).—A lateral out-growth from a vertebra. 
Pleurosteon (Gr. pleuron, a side ; osteon, a bone).—A 
lateral ossification in the anterior portion of 
the sternum of birds. 
Pollex (L. thumb).—The first digit of the manus, the 
thumb. 
Post-axial.—A term applied to that surface of a limb, 
which is posterior, when the limb is at right 
angles to the vertebral column. 
Post-clavicula (L. fosé, after; clavicula, the collar 
bone).— A bone of the pectoral arch in 
certain Teleostean fishes. 
Posterior (L. following after).— Towards the tail ; 
behind. 
