8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



like processes, carrying along one or both sides a row of coarse spines 

 as in figure 5. There are sometimes six or eight such processes on each 

 antenna, projecting in all directions and giving the appendage a de- 

 cidely bizarre appearance. Nothing of this sort has ever been reported 

 upon free-swimming copepods, and hence it may be regarded as a 

 special modification for a special mode of life. Furthermore, the first 

 antennae are short and curve around the front of the head in such a 

 way as to ofl:er least resistance to forward progress. At the same time 



Fig. 5. — c, first antenna of a female Rafhbuniila curticaiida, a 

 sand dweller; d, first antenna of a female Echinoconms pcctinatiis, 

 a sand dweller. 



the frontal margin is thereby furnished with a highly sensitive arma- 

 ture admirably suited for guidance. 



Of course these copepods cannot indulge in free-swimming, since 

 there is no room for it within the sand and mud, and the copepods 

 come out into the open water very seldom, if at all. We therefore 

 find, as would be expected considerable modification of the swimming 

 legs in some of the species. The long plumose setae, so useful in 

 swimming, partially or wholly disappear and are replaced by stout 

 spines. In figure 6 all the first four pairs of legs are modified in this 

 way, and it is quite evident that they are thus made more serviceable 



