14 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



Exopod of third pleopod two-jointed, 



Pleopods of the fourth and fifth pairs have the endopods thick, 

 fleshy, with transverse folds, the exopods two-jointed. 

 The type is Jmrladm^ armatu.^ (Milne Edwards)." 



ISOCLADUS MAGELLANENSIS, new species. 



Body less than twice as long as wide, 4 nnn. : 7 mm. Head Avider 

 than long-, with the front marginate and produced in a small median 

 point. The eyes are small, composite, and situated in the post-lateral 

 angles of the head. The first pair of antenna have the first article 

 a little longer than wide; the second article is somewhat shorter than 

 the first — about half as long; the third 'is one and a half times longer 

 than the second, and narrower. The flagellum is composed of 11 



articles and extends to the middle of the 

 second thoracic segment. The second pair 

 of antennt^?, wnth a flagellum of 13 articles, 

 extend to the posterior margin of the 

 third thoracic segment. 



The first segment of the thorax is longer 

 than any of the six following segments. 

 The seventh segment is produced in the 

 middle in a long, backwardly directed 

 Fig. IS.— isocLADus MAGELLANENSIS. proccss, whlcli cxtcuds almost to the tip 

 ABDOMEN AND LAST THREE THo- ^ ^j tcrmiual abdomiual segment. The 



RACIC SEGMENTS OF MALE. X 9|. _ _ _ » 



epimera are not distinct from the seg- 

 ments, but are produced post-laterall}" in narrow processes. 



The abdomen is composed of two segments, the first of which has 

 suture lines at the sides, indicating other coalesced segments. The 

 terminal segment is triangulate, with the apex rounded. The branches 

 of the uropoda are alike in size and shape and are subequal in length. 

 Each is nearly three times as long as broad, with the extremity 

 roundly truncate. All the legs are ambulatory. 



This species is close to Isocladus splnujer (Dana), but differs in the 

 much wider exopod of the uropoda, which is not acuminate and curved 

 outward at the tip, in the more rounded apex of the endopod of the 

 uropoda and in the longer process of the first abdominal segment. 



Only one specimen, a female, comes from Mayne Harbor, Owen 

 Island, Straits of ]Magellan, 



The type is in the Museum of Comparative Zoology at Harvard 

 University, Cat, No. 6960, M. C, Z. 



Genus DYNAMENKLLA Hansen. 



Sixth and seventh thoracic segments without processes. Abdomen 

 composed of two segments, the first of which is not produced back- 



« Sphxroma armata Milne Edwards, 



