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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVII. 



of the segments, are drawn out in acute processes in the first three 

 segments; those of the following segments are more nearl}- regular in 

 outline. 



The abdomen is somewhat broader than the thorax, although this 

 expansion of the abdomen does not show in a dorsal view. The first 

 segment is about equal in length to the last thoracic segment, and is 

 marked on either side by two suture lines, indicative of coalesced seg- 

 ments. The terminal segment is entire and not produced, being 

 evenly rounded in outline. The anterior portion of the segment is 

 convex, with a longitudinal series of four small tubercles on either 

 side of the median line, the two series being close together. The pos- 

 terior extremity of the segment is marked by a prominent transverse 

 elevation. 



The inner immovable branch of the uropoda is narrow, elongate, and 

 pointed posteriorly; it extends to the extremity of the al)domen. The 



outer mobile branch is furnished on its lat- 

 eral margin with five strong teeth. Both 

 branches are of equal length. 



The first three pairs of legs are slender 

 and are furnished with long hairs. The 

 other four pairs are somewhat stouter. 



Ten specimens were collected at Sausa- 

 lito, California, by Dr. Ritter and party. 



This species is perhaps more closely re- 

 lated to Spha^roiiia sieholdn Dollfus" from 

 Japan than it is to any of the known species 

 of the genus from the Pacific coast of North America. It differs, how- 

 ever, from that species in having a prominent transverse elevation on 

 the posterior portion of the terminal segment, while in S. sleholdii the 

 posterior part of the segment is distinctly concave; in having five teeth 

 on the lateral margin of the outer uropod, while in X sieboldtl there 

 are seven; in having fifteen joints to the flagellum of the second pair 

 of antennge, this organ in S. sleholdii having a fiagellum composed of 

 only ten joints; in having two longitudinal series of four small tuber- 

 cles, one on either side of the median line on the terminal abdominal 

 segment, while in S. sieholdll the granulations on the caudal segment 

 form, in the middle, two divergent lines; and in having the body cov- 

 ered with minute granulations, in S. sleholdii the granulations being 

 strong and more prominent. 



The type is in the Museum of the University of California. The 

 co-type is in the U. S. National Museum, Cat. No. 28768. 



Fig. ].— Abdomen of Sph.eroma 

 pentodon. x 8. 



« Notes from the Leyden Museum, XI, 1889, pp. 93-94, pi. v. 



