182 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



but a .short distance beyond the tip of the terminal segment. The 

 branches are equal in length. The outer branch is narrower than the 

 inner one, and is pointed at its extremity. The inner branch is 

 obliquel}^ truncate, the inner post-lateral angle being widely rounded, 

 the outer one being acute. Both are denticulate and furnished with 

 numerous spines. The basal article of the uropoda extends about half 

 the length of the terminal segment of the abdomen. 



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

 latory. In the first three pairs the carpus is armed with one spine, 

 the merus with two. 



^GA ARCTICA Liitken. 



^ga Arctica Lutken, Vid. Medd.- Nat. For., 1859, p. 71, pi. lA, figs. 1-3.— 

 ScHicEDTE and Meinert, Naturh. Tidsskrift (3), XII, 1879-80, pp. 374-375.— 

 Hansen, Videnskabelige Meddelelser fra den Naturhistoriske Forening i 

 Kj0benhavn, 1887-88, pp. 183-184.— Richardson, American Naturalist, 

 XXXIV, 1900, p. 218; Proc. U. S. Nat. Mus., XXIII, 1901, p. 522. 



Localities.. — Umanekand Hundeoerne near Egedesminde, Greenland; 

 also Iceland and Finmark. 



Found on Soinnioims raicrocepJialus. 



Body oblong-ovate, nearly two and a half times 

 " longer than broad, li mm. : 34 mm. 



Head twice as wide as long, 3 mm.: 6 mm., 

 with the anterior margin widely rounded and 

 produced in a small median point between the 

 basal articles of the first pair of antenme. Eyes 

 large, ov\al, composite, occuj)ying almost the 

 entire surface of the head, and nearly, but not 

 quite, contiguous in the median line. The first 

 pair of antenna' have the first two articles short 

 and subequal, neither article being dilated; the 

 third article is a little longer than the first two 

 taken together. The flagellum is composed of 

 eighteen articles and extends almost to the 

 middle of the first thoracic segment. The 

 second pair of antenniv have the first three arti- 

 cles short and subequal; the fourth and fifth are 

 subequal and each is about twice as long as the 

 third. The flagellum is composed of twent3'-five 

 articles and extends to the posterior margin of 

 the second thoracic segment. The maxilliped 

 has a palp of five articles. The frontal lamina or inter-antennal plate 

 is somewhat triangular in shape, the apex pointing downward on the 

 ventral side, the base meeting the apex of the median point of the 

 frontal margin. 



Fig. 165.— .Ega arctica 

 (After Sars). a, First 

 and second antenn.e. h. 

 General figure, x 3. 



