SALENIA MILIARIS. 



45 



form on the sides of the ambulacral areas the notches for the gills (PI. 20, 

 figs. ;3, 3), one of the zones extending further into the actinal system than 

 the other (PI. 20, fig. 3) ; while in very young specimens of -3 ram. the outline 

 of the actinal system is symmetrical. 



Sai.exia vabispista. 



Flu. 



In the different species of Salenia one or more plates are double, the 

 ambulacral tubercle extending across adjoining plates, each of which has 

 a pair of pores. In Salenia varispina, Fig. 72, it is the second and third 

 plates which are thus constructed (PI. 21, fig. 6.) In a specimen measuring 

 only 1.9 mm. it is the second plate, and in that specimen the plate appears 

 as an intercalated one (the third), the primary tubercle of the second plate 

 not having as yet encroached upon the third plate (PI. 21, (ig. 5). In the 

 older specimen (PI. 21, fig. 6) the tubercles of the second and third plates 

 have encroached upon the intercalated plates, Fig. 73, on one side of the 

 ambulacrum, while on the other the tubercle of the second plate has gone 

 over the intercalated plate and that of the third plate has not yet en- 

 croached upon the intercalated plate. 



S 1I.KXIA MII.IAK1S. 



In a young S. miliaris (PI. 20, fig. /) it is the second which is a double 

 plate, Fig 74. In older specimens the actinal plates have been partly 



