ISOPODS 215 



lateral parts, which are not distinctly separated from the dorsal parts of 

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

 Those of the following segments are more nearly 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 segments. The ter- 

 minal segment is entire, and not produced, 

 being evenly rounded in outline. The ante- 

 rior 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 posterior 

 extremity of the segment is marked by a „ ,' ».. ,0., 



•' '-' ^ tiG. 96. Abdomen of Sphceroma j>en- 



prominent transverse elevation. todon^'^. nov. (xs). 



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

 pointed posteriorly ; it extends to the extremity of the abdomen. The 

 outer mobile branch is provided on its lateral 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 Sausalito, California, by Dr. Ritter 

 and party. 



This species is perhaps more closely allied to Sphceroma sieboldii Doll- 

 fus ^ from Japan than it is to any of the known species of the genus 

 from the Pacific coast of North America. It differs, however, from that 

 species in having a prominent transverse elevation on the posterior por- 

 tion of the terminal segment, while in S. sieboldii the posterior part of the 

 segment is distinctly concave ; in having five teeth on the lateral margin 

 of the outer uropod, while in S. sieboldii there are seven ; in having 

 fifteen joints to the flagellum of the second pair of antennae, while this 

 organ in S. sieboldii has a flagellum composed of only ten joints ; in 

 having two longitudinal series of four small tubercles, one on either side 

 of the median line on the terminal abdominal segment, while in S. sieboldii 

 the granulations on the caudal segment form, in the middle, two diver- 

 gent lines ; and in having the body covered with minute granulations, 

 while in S. sieboldii the granulations are 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. 28,768. 



1 Notes from the Leyden Museum, xi, pp. 93, 94, pi. 5, 1889. 



