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PROCEEDINGS OF THE NATIONAL MUSEUM 



Figure 9. — Caligus ligatus, new species (holotype male, paratype immature female): 

 first thoracic leg; b, second thoracic leg; c, third thoracic leg; d, fourth thoracic leg. 



segment; lateral and distal margins of second segment continuous, 

 segment with semicircular appearance. Endopodite two-segmented, 

 proximal margin of first segment indistinct; second segment semi- 

 circular, similar to second exopodite segment in shape (fig. 9c). 



Fom'th thoracic leg uniramous, three-segmented. Protopodite one- 

 segmented, almost equal in length to combined lengths of two segments 

 of exopodite. Proximal surface of protopodite with small projection 

 on inner medial portion forming articular surface; distal surface with 

 small spine on outer portion, knoblike articular sm'face from median 

 portion. Fhst segment of exopodite short, distal end forming shelf- 

 hke projection from outer margin of segment and bearing single, weU- 

 developed spine. Second segment of exopodite with slender, rodlike 

 process overlying inner margin of first segment. Outer and distal 

 margins of second segment continuous, with four strongly developed 

 spines spaced along margin, proximal spine in close proximity to ter- 

 minal spine of first segment; terminal spine longest, proximal three 

 spines of approximately equal length. Basal portion of terminal and 

 adjacent two spines surrounded by frilled margin, that of terminal 

 spine arising from spinelike projection of inner margin. All major 

 spines with membrane along inner and outer margins, membranes of 

 terminal spine minute, discontinuous (fig. QcT). 



The character of the membranes, spines, and setae on the thoracic 

 legs is given below. The thoracic legs of both the male and the 

 immature female are identical except for the fourth thoracic leg which 



