230 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 5 



PLATE 27 



Fig. 1. Tetrahalanus polygenus. A. maxilla. B. labrurn, C. mandible. 



D. median segment of cirrus VI, showing one row of spines. 



E. interior of tergum. F. exterior of tergum. G. interior of 

 scutum. H. exterior of scutum. I. side view of shell. J. top 

 view of shell, showing cover-plates in position. 



