470 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



■&-X--.~c6- 



Fig. 200. — Genus Pleurotoichus Levinsen, 1909 



A-J. Pleurotoichus clathralus Harmer, 1902. A. Ends of several branches, 

 natural size. B. Operculum and labium (I) from a dry specimen. The arrow 

 indicates the entrance of the compcnsatrix. C. Part of the frontal surface of a 

 branch; m. lateral margin of the frond, the epitheca of which covers a continu- 

 ous marginal cavity (?n. c.) strengthened by calcareous bars (c. b.) in its frontal 

 wall. Two of the opercula B and B' are different from the others (A). D. The 

 zooecium B and parts of its neighbors, of the preceding figures; d. w. distal wall 

 of B; p. w. proximal wall of distal neighbor. (For X see fig. M). E. Basal 



