158 



BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



FIG. 137. ALCIRONA KREBSII 

 (AFTER HANSEN). a, DORSAL 



VIEW OF HALE. X \ 5 -. 6, LAT- 

 ERAL VIEW OF ADULT MALE. 



xy. 



twice as long as the second; the third is as long as the first; the fourth 

 is twice as long as the third; the fifth is twice as long as the fourth. 

 The flagellum is composed of thirty-nine articles. The second pair of 

 antennae extend to the posterior margin of the seventh thoracic seg- 

 ment; the peduncle extends to the posterior margin of the first thoracic 



segment. The maxilliped is composed of 

 seven articles. The palp of the mandibles 

 is composed of three articles. The frontal 

 lamina has the anterior portion broad, the 

 posterior end attenuated; the anterior mar- 

 gin is triangulate. 



The first segment of the thorax is one and 

 a half times longer than any of those follow- 

 ing. The epimera are distinct on all the 

 segments, with the exception of the first. 

 The last four are crossed obliquely by an 

 arched carina; the first two are crossed lon- 

 gitudinally. The outer post-lateral angles 

 of the first two epimera are rounded; those 

 of the last two are acutely produced beyond 

 the posterior margins of the segments. The last three segments of 

 the thorax are covered with short stiff hairs. 



The first two segments of the abdomen are entirely concealed by 

 the seventh thoracic segment. The 

 sixth or terminal segment is trian- 

 gular in shape, with the apex nar- 

 rowly rounded and furnished with 

 six spines. The entire abdomen is 

 densely covered with short stiff hairs 

 or bristles. The inner branch of the 

 uropoda is broad and widely rounded 

 at the posterior extremity ; it extends 

 as far as the extremity of the abdo- 

 men. The outer branch is as long 

 as the inner branch, is half as wide, 

 and has the extremity narrow. The 

 margins of both branches are fur- 

 nished with spines, and stiff hairs 

 or bristles densely cover the whole dorsal surface. The inner angle 

 of the peduncle is produced and extends a little beyond the middle of 

 the terminal abdominal segment. 



The first three pairs of legs are prehensile, the last four pairs 

 ambulatory. 



FIG. 138. ALCIRONA KREBSII. a, MAXILLIPED. 

 x 51|. 6, MANDIBLE, x 51f. c, FRONTAL 

 LAMINA, x 51|. 



