Bull. U. S. F. C. 1900, Vol. 2. — H. L. Clark. (To face page 264 
Plate 1 5. 
Figs. 1-4. Ophialcsea glabra. — Fig. 1, upper surface, > 2. Fig. 2, under surface, x 2. Fig. 3, side view of 3 joints from near middle of 
arm, showing the number of arm-spines, x 2. Fig. 4, one spine from near middle of arm, x 15. 
Figs. 5-8. Ophiacantha ophiactoides. — Fig. 5, upper surface, x 10. Fig. 6, under surface, x 10. Fig. 7, side view of 3 joints from near 
middle of arm, showing the number of arm-spines, x 10. Fig. 8, one spine from near middle of arm, x 65. 
Figs. 9-12. Ophioplinthaca spinissima. — Fig. 9, upper surface, x 3. Fig. 10, under surface, > 3. Fig. 11. side view of 3 joints from near 
middle of arm. showing the number and proportions of the arm-spines, x 3. Fig. 12, one spine from near middle of 
arm, x 10. 
