ISOPODS OF NORTH AMERICA. 



FIG. 677. HYPER- 

 GNATHUS TEX- 

 EXSIS. UROPOD. 

 x51|. 



The five anterior segments of the abdomen are subequal in length, 

 the first two not being covered at the sides by the seventh thoracic 

 segment. The sixth or terminal segment is posteriorly 

 produced to a triangular extremity. The uropoda 

 extend some distance beyond the terminal segment of 

 the body. The peduncle extends beyond the terminal 

 abdominal segment. The outer branch is twice as long 

 as the peduncle. The inner branch is placed at the 

 inner distal angle of the peduncle and is less than half 

 the length of the outer branch. 



The color is a light yellow, with irregular markings 

 of brown on the posterior margins of the segments and 

 on the lateral parts. The head is thickly covered with 

 brown markings, which on the produced portion are 

 arranged in definite transverse lines, but on the remain- 

 ing surface are arranged irregularly around small, 

 rounded, yellow areas. The abdomen is very closely 

 covered with the brown as is also the posterior half of the outer uropod. 



Types, Cat. No. 32075 U.S.N.M., collected by H. S. Barber in Texas. 



114. Genus ACTONISCUS Harger. 



Head produced in three lobes, a median lobe and an antero-lateral 

 lobe on either side. Second pair of antennae with the flagellum com- 

 posed of four articles. First maxillae with inner lobe furnished at 

 the tip with two bunches of hairs; outer lobe furnished with numer- 

 ous spines. Second maxillae small, not larger than first maxillae, 

 with no indication of lobes at the tip. Masticatory lobe of maxilli- 

 peds truncate at the tip; palp with joints indistinctly defined. 



Abdomen not abruptly narrower than thorax; the first two segments 

 are covered laterally by the last thoracic segment; lateral parts of the 

 third, fourth, and fifth segments well developed; terminal segment 

 with apex not produced. 



Basal article of the uropoda large, dilated, and simulating the epim- 

 era of the fifth abdominal segment; both branches of the uropoda 

 short, styliform, the outer one inserted about the middle of the inner 

 margin of the peduncle. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS ACTONISCUS. 



a. Middle frontal lobe of head acute; antero-lateral lobes rounded. Second and third 

 articles of flagellum of second antennae equal and longest. Terminal segment 

 of abdomen broadly rounded. Surface of body smooth. Fifth article of the 

 peduncle of the second antennae longer than the fourth; terminal article of 

 flagellum minute. Post-lateral angles of the first thoracic segment not produced. 



Actoniscus ellipticus Harger 



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