NEW ISOPOD CRUSTACEANS— RICHARDSON. 



21 



The t3'pe of the genus is Cassidias argentinea, the description of 

 which follows. 



CASSIDIAS ARGENTINEA, new species. 



Body oval, contractile into a ball. Head wider than long, with the 

 front marginate and produced in a small median point. The eyes are 

 small, composite, and placed in the post-lateral angles. The first pair 

 of antenna have the first article oblong, about one and a half times 

 longer than wide; the second article is minute, round; the third article 

 is narrow, elongate, and about twice as long as the second. The fla- 

 gellum is composed of nine articles and extends to the middle of the 



e>-^^-A. 



/ 



a 



h 



Fig. 26.— Cassidias argentinea. a, Maxilliped of female. x52. ft, First maxilCa of female. 

 X 52. c, Abdomen AND last thoracic segment of female. x4f. d, Third pleopod. x 39. 

 e, Fourth pleopod. x 39. /, Lateral view of abdomf.n. a. Abdomen, h, Terminal view of 

 abdomen. 



first thoracic segment. The second antennw, with a flagellum of ten 

 articles, extend to the posterior angle of the first thoracic segment. 



The first segment of the thorax is a little longer than any of those 

 following. Epimera are not distinct on an}^ of the segments, but they 

 are indicated b}^ faint lines of depression. The lateral parts of the 

 segments are drawn out in narrow processes. 



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

 three suture lines on either side, indicating coalesced segments. The 

 terminal segment is produced in a truncate extremity, which has a 

 small rounded excavation in the center. The notch is entirely con- 

 cealed in a dorsal view, and is formed by the infolding of the sides. 



