ISOPODS OF NORTH AMERICA. 2t)5 



segment. Both branches are equal in length and similar in shape. 

 The outer branch is about half as wide as the inner branch. The 

 branches are of equal width throughout their lengthy the outer branch 

 is rounded posteriorly; the inner branch is obliquely truncate, with 

 post-lateral angles rounded. 



The legs are all prehensile with long curved dact3 r li. There is no 

 carina on the basis of any of the legs. 



The color is brown, with a transverse band of yellow along the pos- 

 terior margins of all the segments. The epimera are also yellow. 



43. Genus IRONA Schioedte and Meinert. 



Body oval. Head deeply immersed. 



First pair of antennae widely separated at the base, rather com- 

 pressed. 



The anterior margin of the first thoracic segment widely sinuated, 

 the ante ro- lateral angles short. First thoracic segment manifestly 

 longer than the second. Anterior epimera rather long and narrow, 

 gradually increasing in width; the posterior ones rather short and 

 rather wide. 



Body of female asymmetrical; that of male more symmetrical. 



Abdomen continuous with thorax, not narrower than thorax; deeply 

 immersed. Carina on the four posterior pairs of legs almost absent. 



IRONA NANA Schioedte and Meinert. 



Irona nana SCHICEDTE and .MEINERT (3), XIV, 1883-84, pp. 390-395, pi. xvu, 

 figs. 6-11. RICHARDSON, Proc. U. S. Nat. Mus., XXIII, 1901, p. 531. 



Localities. Caribbean Sea and Atlantic Ocean; St. John; St. Bar- 

 tholomew; Rio Janeiro; Harrington Sound, Bermudas (collected by 

 Doctor Linton). 



Found parasitic in gills of Hemirhampfais sp. ; on Atherina sp. ; on 

 Atherina harrinytonensis. Doctor Linton says the attachment is 

 voluntary, the parasite frequently leaving the host when disturbed. 



Body subovate or ovately produced, very much twisted, rather con- 

 vex, more than one and a half times or twice as long as wide (5 : 3 

 or 2 : 1). 



The head is small, subtriangular or subconical, one-third or one- 

 fourth as wide as the fourth segment of the thorax (3 : 1 or 4 : 1), much 

 wider than long (5:4), deeply immersed, with the front bent down- 

 ward and narrowly rounded. The eyes are large and subpentagonal. 



The first pair of antenna? are rather compressed, rather stout, widely 

 separated, reaching with the fifth article the anterior angle of the first 



See Schkedte and Meinert for characters of genus, Nat. Tidsskr. (3), XIV, 

 1883-84, pp. 381-383. 



