AYEAK JAWS 151 



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 setae to each joint. Most of these 

 setas 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 setge, 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 antennae 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 



