Puate 85, 
1-5. Pilematechinus Rathbuni A. Ag.; Station 3374. 
Actinostome and adjacent surrounding plates of a specimen 85 mm. in length. 
. Actinal system of same, seen from the interior of the test. 
Abactinal system and surrounding plates of a specimen 95 mm. in Jength. 
. Abactinal system of same, seen from the interior. 
One of the abactinal plates showing the splitting of a primary interambulacral plate, 
and the resorption of the primary and miliary tubercles; this is also shown in figs. 
1 and 3. 
