ISOPODS OF NORTH AMERICA. 



533 



along 1 its outer (longest) border and across its base by a chitinous rod. 

 The anterior blades, in company with the dorsal portions of the third 

 pair of plates, form the funnel-like anterior end of the marsupium. 



"The details of the thoracic segments are shown in fig. 578c. The 

 first five are crowded together, their fleshy lateral portions strongly 



Fio. 578. STEGOPHKYxrs >IYPTIUS (AFTER THOMPSON), a, HERMIT CRAB WITH PARASITE ATTACHED. 

 x f. 6, ANTERIOR PORTION OF HEAD OF FEMALE (VENTRAL SIDE), c, DORSAL VIEW OF ADULT FEMALE. 

 x 5. d, VENTRAL VIEW OF SAME, x 4J. e, LEFT MAXILLIPED OF ADULT FEMALE, x 10. /, HEAD 



OF ADULT FEMALE (DORSAL VIEW). X llj. g, HEAD OF ADULT FEMALE (VENTRAL SIDE). A, ABDO- 

 MEN AND POSTERIOR PART OF THORAX OF ADULT FEMALE (VENTRAL VIEW). X 5}. 



bent toward the head. The lateral parts of first four segments end 

 in a small roughened boss or cushion, on which the roughened third 

 joint of the pereiopod impinges. This cushion may represent a 

 modified epimeron. Internally to this cushion is a flat shield-shaped 

 area which comes in contact with the abdomen of the host. The 



