I'LATE VII. 



r/), covering plates. 



g, food groove. 



.'/), side plates. 



1. Showing food groove with its covering and side plates, from the base of an arm near its junction 



with the disk. 



2. Same as Fig. 1, from near the base of another arm. 



3. Profile view of side plates of the food groove of tlie disk, between the second and third forks. 



4. Side plates and covering plates of the food groove of one of the arras between the second and third 



forks, from above. 



5. The same as Fig. 4, seen in profile, but above the third fork of the arm. 



6. Profile of side plates and covering plates of an arm between the second and third forks. 



7. Same between the third and fourth forks. 



8. Covering and side plates seen from above between the first and second forks. 

 9i Covering and side plates of the food groove about the middle of the arm. 



10. Profile of covering and side plates towards the end of the arm. 



11. Same plates as Fig. 10, still farther out towards the extremity of the arm. 



12. One of the covering plates of arm near those of Fig, 11, to show its connection with the sup- 



porting side plates. 



13. Side plates of food groove of arm above the second fork, seen in profile. 



14. View from above of covering plates and side plates between the third and fourth forks. 



15. View from above of covering and side plates nearer the extremity of the arm than those of Fig. 11. 



16. Profile of plates still nearer the end of the arm. 



17. Food groove from above, at the second fork. 



