Boone, Crustacea, Cruises of "Eagle" and "Ara," 1921-28 103 



oblique carina runs forward from the lower side of the hepatic spine 

 and downward towards, but not reaching the pterygostomian angle. 

 The posterior margin of the carapace is straight in a median region, 

 but convex laterally, overlapping the first abdominal segment. 



The abdomen is stout, the epimeral region of the first four segments 

 moderately convex, that of the fifth segment also convex, but directed 

 obliquely back, overlapping the proximal part of the long sixth seg- 

 ment. The posterior half of the fourth segment and the entire fifth 

 and sixth segments are carinated sharply in the median longitudinal 

 line, the carina terminating on the sixth segment. The sixth segment 

 is one and one-third times as long as the fifth, and bears on each side 



Text fig. 1. — A. Lateral view of terminal abdominal segments, showing markings 



on the fifth and sixth segments, which are peculiar to P. brasiliensis and P. setif- 



erus. B. Thelycum. C. Petasma of adult male. 



three short, subequally spaced, slightly diagonal linear marks, each 

 consisting of a carina below which is an accompanying sulcus. The 

 telson is short, triangular, tapering to an acuminate point, a deep 

 median longitudinal sulcus with a carinate lateral margin, extending 

 the entire length of the telson. The rhipidura consists of a short 

 peduncle, the inner blade intermediate in length between the telson 

 and the outer blade, which latter is nearly one and one-half times 



