NO. 1175. ISOPODS OF THE PACIFIC COAST— lilCHARDSON. 831 



longer than tlie last abdominal segment. Both branches are similar in 

 shape and size; they are oarlike, with truncately rounded extremities. 



The legs increase slightly in length. The basis of all tlie legs is 

 carinated on the inferior margin. 



Color a light brown, marked with numerous black dots over the 

 whole surface of the body, with the exception of the posterior half of 

 the last abdominal segment and the inner branch of the uropoda, which 

 are a light clear yellow without spots. The outer branch of the uropoda, 

 which is almost black, contrasts in a marked degree with the light inner 

 branch. In the caudal segment the change from the darker to the lighter 

 half is graduated, making the contrast less marked. 



Two individuals of this species were taken ; one by the II. S. Fish 

 Commission steamer Albatross^ station 3L3S, at a depth of ID fathoms, 

 and one by Dr. D. S. Jordan, both at Monterey Bay, California. One 

 was imperfect. 



Type.—^o. 225(57, U.S.i^.M. Monterey Bay. Depth, 19 fathoms. 



When compared with A. Iwris Miers ' from Peru this species differs 

 in the shape of the anterior portion of the head, which in A. Ucvis is 

 narrowed and rounded, while in ^1. occidentaUs it is truncate; in the 

 greater length of the first thoracic segment and the equality in length 

 of the succeeding segments in A. occidentalism while in A. lawis the 

 sixth segment is the longest, the others being of nearly equal length; 

 in the length of the ejumera, which in .1. occidentali.s attain the posterior 

 margin of the corresponding segments, while with .1. Iwris they are all 

 veiy small and somewhat spiniform in the fifth to the seventh segments; 

 in the greater breadth i)osteriorly of the terminal segment of the body 

 in A. Icevis, and in the sha])e and length of the uropoda in the two 

 species, the two branches being of unequal length, lamellate in shape 

 (the inner one the longer), and both shorter than the last segment of 

 the body in A. heins, while in A. californica they are equal in length, 

 similar in shape, oarlike, and longer than the terminal segment. 



Family VII. SFH..55KOMIDyE. 



ANALYTICAL KKY K) THK (iENEKA OF Sl'H.KKOMID.E. 



a. Both exterior and interior branches of uropoda projecting. 



b. Terminal segment of the abdomen excavated at its extremity.. .12. Dynamene. 

 b'. Terminal segment of abdomen entire. 



c. Margins of head not produced; antenn;e conspicuous; legs normal; mandi- 

 bles with five-jointed palp 13. Sphwroma. 



c'. Anterior and lateral margins of head produced, concealing antenna- ; propo- 

 dus of first and second j)air8 of legs dilated, with rellexed dactyliis; man- 

 dibles with three-jointed palp 14. Tecttceps. 



a'. Only exterior branch of uropoda projecting; penultimate abdominal segment in 

 male generallj' produced in spine; terminal segment excavated with median 

 tooth 15. Ciliccea. 



' Proc. Zool. Soc. London, 1877, p. 672, pi. i.x viii, fig. 6. 



