NO. 1175. ISO PODS OF THE PACIFIC COAST—EICIIAIiDSON. 855 



of the mediaii line. The fifth tlioracic segiiieut has twelve spines, six 

 on eitlier side of the median line. The sixth segment has ten spines, 

 five on either side. The seventh and last segment has eight spines, 

 four on either side. 



The abdomen is composed of two segments. The first is short, with 

 twelve spines, six on either side of the median line, the four inner ones 

 being arranged in two longitudinal series, the two upper ones being 

 small, the two low^er ones very long. The terminal segment has the 

 upper surface smooth. This segment terminates in two long divergent 

 spines. There is a single spine on the lateral margin on either side 

 halfway down the segment. The three anterior pairs of legs have 

 each two spines on the coxal joint and one spine on the basis. The 

 body increases in width from the first to the fourth segment, and then 

 decreases in width from the fourth to the terminal segment. 



One specimen from Kyska Harbor, Aleutian Islands, 10 fathoms, 

 collected by Mr. W. H. Ball. 



Type.—^o. 22581, U.S.N.M. 



Our species differs from A. mnrdochi in the absence of spines on the 

 third joint of the second pair of antennie; in the greater length of this 

 joint in relation to the preceding joint; in the greater length of the two 

 following joints ; in the presence of a single spine on the anterior part of 

 the head, while in A. murdochi there are three, and of two spines on the 

 posterior part, while in A. murdochi there are four; in the absence of two 

 small spines just below the constriction in the fourth segment; in the 

 absence of the row of spines on the terminal segment of the body; and 

 in the presence of two spines on the coxal joint and one on the basal 

 joint of the legs, while in A. murdochi there is but one spine on the 

 basal joint. 



This species is also distinguished from A. hystrix in the presence of a 

 single median spine on the anterior part of the head, while in A. hystrix 

 there are two, one on either side of the median line and widely sepa- 

 rated; in the presence of two spines on the posterior part of the head, 

 while in A. hystrix there are four; in the absence of the double row of 

 spines on the terminal segment of the body; and in the absence of the 

 spine at the articulation of the third joint of the second pair of antennai. 



64. ARCTURUS MURDOCHI Benedict. 



Arctiiriis murdochi Benedict, Proc. Biol. See. Washington, XII, 1898, pp. 49, 50. 

 Habitat. — Point Franklin, Alaska. 



65. ARCTURUS GLABERi Benedict. 

 Arcturua i/labrus Benedict, Proc. Biol. Soc. Washington, XII, 1898, p. 46. 



Habitat. — Bering Sea. 



' Glabnts by error. 



