WEAK JAWS tof 
particles from the other appendages within their reach. 
For this brushing service they must be well adapted, 
since in ordinary adult specimens there are from a hun- 
dred to a hundred and fifty joints in the flagellum, and 
from eight to twelve sete to each jot. Most of these 
setze are only slightly bent, but armed on the outside of 
the curve with a great number of variously shaped teeth. 
On either side of each bundle, however, there is a very 
long seta, convolutely curved inward at the extremity, and 
along nearly its whole length densely furnished with long, 
slender, secondary setze, arranged in a double series on the 
inner side of the curve. Already in the megalopa stage, 
Professor Smith found that the mandibles had become thin 
and foliaceous and completely consolidated with the walls 
of the oral opening. This extremely unusual condition of 
those organs persists in the adult, and seems to have per- 
plexed the few naturalists who have earlier examined them. 
It must be a subject of surprise that a crustacean of such 
a family as this should be able to dispense with the biting 
power usually so strongly developed in the mandibles. But 
we are told that in all specimens examined the alimentary 
canal was filled with fine sand, and as the material from 
the stomach showed under the microscope a small quantity 
of vegetable matter, the inference is not improbable that, 
much after the fashion of the earthworm, the creature ob- 
tains nutriment from the sand which it passes through its 
body. Milne-Edwards was evidently under the impression 
that the true second segment of the pleon in this genus 
was its first segment, but Professor Smith has shown very 
clearly that the first pleon-segment is in the adult coalesced 
with the trunk, a thing very unusual but none the less in 
this case quite to be depended on. 
Remipes, Latreille, 1806, has the peduncle of the 
second antennz large, but the flagellum quite small. The 
first segment of the pleon is free, the telson lanceolate, of 
great length. As in Hippa, the female carries appendages 
on the second, third, fourth, and sixth segments of the pleon. 
The founder of the genus and several writers since have 
supposed the first pleon-segment to be the last segment of 
