176 BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



FIG. 79. OPHIOCRASIS DICTYDISCA. a-c, X 7; d-g, X 11. a, FROM ABOVE; b, FROM BELOW; c, SIDE 



VIEW OF TWO ARM JOINTS NEAR DISK; d, A YOUNGER SPECIMEN, FROM ABOVE; C , THE SAME, FROM BELOW; 

 /. SIDE VIEW OF THREE ARM JOINTS NEAR DISK; (J, ANOTHER YOUNG SPECIMEN FROM ABOVE, SHOWING 

 THE INEQUALITY OF THE TWO TRIOS OF ARMS. 



