34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



(formerly round) filament, which is beautifully preserved in some 

 specimens (fig. 8, pi. 22). The fringe of filaments often overlap 

 those of the adjoining exopodite so as to form an imbricating series 

 of fringes the entire length of the body. 



An exopodite 3 mm. in length has attached to it 42 filaments that 

 average about 12 to 14 to the millimeter in the proximal portion, 

 and 14 to 16 towards the distal end ; they increase gradually in length 

 from the proximal end until on the distal section they may be as long 

 as the entire exopodite. A rusty specimen laid aside as of little value 

 proved on cleaning to have the filaments preserved as long, slender 

 cylinders or tubes (see fig. 8, pi. 22). 



Most of the fossil specimens have the fringes extending forward 

 and outward, but when the animal was living they undoubtedly ex- 

 tended outward and backward so as not to impede its forward move- 

 ment. 



As mentioned under Cephalic appendages, there is good reason to 

 think that the two posterior oral appendages (maxillulae and maxillae) 

 have in addition to the simple jointed endopodite an exopodite similar 

 in structure to that of the thoracic limbs. 



Epipodite. — A single specimen shows what I thought in 191 2 to be 

 a large epipodite or branchiae,' but which I have now decided to be 

 several of the fringed exopodites pressed down together and more or 

 less macerated in the contents of the body which were squeezed out 

 on that side. It was only after finding a number of examples showing 

 the fringed exopodites arranged in this manner but not pressed into 

 each other that I gave up the view that a large epipodite was present. 



Several specimens have been found since 1912 that indicate the 

 presence of a small oval flattened lobe attached to the dorsal side of 

 the protopodite, or it may be to the proximal joint of the exopodite. 

 but it may be that this appearance is caused by the manner in which 

 the protopodite and the segments of the body are matted down to- 

 gether ; some of the thin oval bodies, however, are so clearly defined 

 that they suggest the presence of a small epipodite, but I do not 

 consider the evidence sufficient to warrant representing them on the 

 restoration of the thoracic limb. 



Functions of appendages. — The proximal joints of the antennae 

 may have assisted in mastication and may have had a sensory func- 

 tion. The proximal joints of the mandibles undoubtedly served in 

 mastication, but whether those of the slender leglike maxillulae and 

 maxillae aided is undetermined, as nothing has been seen of either 



* Smithsonian Misc. Coll., vol. 67, pis. 29, 32, 1918. 



