156 
GAMMARIDtE. 
nearly the same length, but the third is much shorter 
and slighter, and the flagellum is not more than twice 
the length of the last joint of the peduncle. The in- 
ferior antennae are but little longer than the superior ; 
the joints of the peduncle are more nearly equal in 
length, but the last is more slender than the preceding ; 
the flagellum is but little longer than the last joint of 
peduncle. The mandibles appear to be very strong, — 
they are exceedingly hollowed ; the incisive margin is 
smooth, and has the extremities rounded ; within there 
is a second plate, but of much smaller dimensions ; 
nearer the head stands a very large molar tubercle. 
The appendage to the mandible is three-jointed, the 
second, longer than either of the others, is triangular 
in its diameter, and strongly curved. The foot-jaws are 
short and strong, — the third joint is furnished with a 
large squamous plate, the outer margin of which is 
rounded, and the inner straight, fringed with spines and 
small hairs alternately, and increasing in length ; the 
fifth joint is broad, longer than the fourth or sixth, 
which last is ovate, and supports a strong finger. The 
first pair of arms are subchelate, — they are not very 
long, and have the wrist as long as the hand ; the infero- 
anterior angle is anteriorly produced into a rounded lobe, 
the inferior margin of which is fringed with a few hairs ; 
the hand is elongate-ovate, the palm occupies nearly the 
whole length of the inferior margin, and is imperfectly 
defined by a small tooth, and fringed with a series of 
equidistant cilia of equal length ; the finger appears to 
be scarcely as long as the palm, — the whole organ is but 
inefficient in its prehensile powers. The second pair of 
arms are about the same size as the first, but they ap- 
pear to possess no prehensile capability; the hand is 
longer than the wrist, and dilated on the superior mar- 
