ISOPODS OF NORTH AMERICA. 



831 



posterior maro-in. The first pair of aiitonnje liave the basal article 

 larj^e and dilated; the second and third articles are subequal and are 

 shorter and smaller than the first; the fourth article is twice as long 

 as either of the two preceding- articles. The first antenna' extend to 

 the end of the second article of the pcxiuncle of the second pair of 

 antenna^. The first article of the second antenna; 

 is short, not longer than the basal article of the 

 first pair of antennte; the second article extends 

 to the end of the first antennae; the third article 

 is three and a half times longer than the second; 

 the fourth is nearly twice as long as the third; 

 the fifth article is nearly as long as the fourth; 

 the flagellum is composed of six articles, the 

 first one of which is about three 

 times longer than the second or 

 following articles. The second 

 antenntt are longer than the 

 bod}'. The palp of the maxilli- 

 peds is composed of five articles. 

 The first three segments of 

 the thorax are subequal, each 

 being 2 mm. in length. The 

 fourth segment is twice as long 

 as either of the three preceding 

 segments and is -i mm. in length. 

 The fifth segment is 2i nun. 

 long. The sixth and seventh 

 segments are each 2 mm. in length. Kpimera are not represented on 

 the first thoracic segment. The epimera of the three following seg- 

 ments are small and occupy the antero-lateral angles. In the last three 

 segments the epimera are large and latei'ally produced. 



The first two segments of the abdomen are short and sube([ual. 

 The third or terminal segment is long and tapers to a blunt extremity. 

 The first four pairs of legs extend forward and are strongly ciliated. 

 The last three pairs are ambulatory. 



Fig. 361.— Arcturus glaber 

 (After Benedict), x 1^. 



Fig. 362. — Arcturus 



GLABER. MAXIL- 



LIPED. X Hi. 



ARCTURUS PURPUREUS Beddard. 



Arctnms purpureus Beddard, Proc. Zool. Soc. Loudon, 188G, p. 109; Report on 

 the Sfientific Results of the Exploring Voyage of H. M. S. Challenger, 

 Zool., XVII, 1886, pp. 112-118.— R1CHAUD8ON, Proc. U. S. Nat. IMns., XXIII, 

 1901, p. 546. 



Locality. — Ofi' Sombrero Island. 

 Depth. — 450 fathoms. 



"A single specimen of this species was dredged in the North Atlantic 

 at station 23 from a depth of -loO fathoms. 



