NO. 1479. NEW ISOPOD CRUSTACEAXS—RICHARDSON. 15 



ward in an}^ process. Terminal abdominal segment usually with a 

 notch, which may or may not be connected anteriorly' with a trans- 

 verse foramen. Sexes alike.'* 



Uropods always with exopod at least half as long as endopod. 



Exopod of third pleopod unjointed. 



Fourth and fifth pleopoda have both branches subsimilar, with deep, 

 transverse folds, flesh}-, and without marginal seta?. Exopod of fifth 

 pleopod generally distinctly two-jointed. - 



Hansen makes Dyvataene perforata Moore the type of this genus. 



DYNAMENELLA AUSTRALIS, new species. 



Body 4 mm. wide: To- nun. long. Head quadrangular, frontal mar- 

 gin produced in a small median point. The first pair of antenna? 

 extend to the post-lateral angle of the first thoracic 

 segment; the flagellum is composed of ten articles. 

 The second pair of antenna? reach the posterior angle 

 of the fourth thoracic segment; the flagellum is com- 

 posed of sixteen articles. 



The segments of the thorax are similar in shape 

 and size. The epimera are not distinct from the seg- *"'■• i'->-dyxame- 



^ " XELLA AVSTRALIS. 



ments. The lateral edges of the segments are almost abdomen and 

 straight. Two rows of tubercles extend along the ^•^''^ thoracic 



O '=' SEGMENT. X Dj. 



posterior margin of the seventh segment, the two 



middle tubercles of the last row being very broad; the other segments 



are entirely smooth. 



The two segments of the abdomen are thickly granulated. Eight 

 tubercles are placed in a transverse line on the first segment. On 

 the terminal segment there are three rows of four tubercles in each 

 row in transverse series. In some of the specimens the two middle 

 tubercles of the last row are wanting. The abdomen narrows rapidly 

 toward its extremity, which is deeply excavate, the excavation being 

 wider anteriorly than posteriorly. A small tubercle is placed just 

 above the excavation. The uropods extend but a little beyond the 

 extremity of the abdomen. The inner branch is narrow, long, and 

 rounded posteriorly. The outer branch is leaf -shaped, bi'oad. pointed 

 at its extremity, and somewhat longer than the inner l)ranch. 



Both branches of the fourth pleopods are similar, fleshy, crossed 

 with transverse folds, and the exo^wd is unjointed. The exopod of 

 the thij-d pleopod is also unjointed. 



« Although the forms which I believed to be the females of Dynameneila perforata 

 may prove to be young males, those supposed by Doctor Hansen to be the females 

 of this species can not be so considered, inasmuch as adult males are found exactly 

 similar to them. The females of Dynameneila perforata probably resemble the males, 

 as do the females of all the species which I have referred to Doctor Hansen's genus. 



