Plate 74. 

 1-5. Urechinus giganteus A. Ag. ; Station 3431. 



1. Alxiotinal system and adjoining plates of specimen 93 mm. iu length. 



2. The same, seen from the interior of the test. 



3. Abactinal extremity of the odd ambulacrum, seen from the interior. 



4. Abactinal extremity of same, somewhat more enlarged than tig. 3. 



5. Twelfth abactinal interambulacral plate from the mouth, showing the resorption of some ^i 



primary and miliary tubercles. 



6-8. Urechinus Naresianus A. Ag. ; " Blake " Exp., Station 222, off St. Lucia. 



6. Actinal system and surrounding plates of specimen 13 mm. in diameter. 



7. Abactinal system of same specimen. 



8. Anal system and rudimentary anal fasciole of the same. 



i 



