ISOPODS OF NORTH AMERICA. 2()5 



seoniciit. Both hranchos arc (miuuI in Iciiotli and similar in shape. 

 The outer branch is about halt" as wide as the inner branch. The 

 l)ranches arc of cciual width througliout their Icng-th; the outer branch 

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

 post-lateral ang-les rounded. 



The leo's are all i^rehensile with long- curved dact}^!. 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 cpimera are also yellow. 



43. Genus IRON A Schioedte and Meinert." 



Body oval. Head deepl}^ immersed. 



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

 pressed. 



The anterior margin of the first thoracic segment widely sinuated, 

 the antero-lateral angles short. Fii-st thoracic segment manifestly 

 longer than the second. Anterior cpimera 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 Schicedte and Meinert. 



Irona nana Schicedte and .Meineht (3), XIV, 1883-84, pp. 390-395, pi. xvn, 

 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 Hemirliamplms sp. ; on Atherina sp.; on 

 Atheriiia harringtonensis. Doctor Linton saj's 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 iialf times or twice as long as wdde (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 -t : 1), nnich 

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

 ward and narrowly rounded. The e3'es are large and subpentagonal. 



The tirst pair of antennte are rather compressed, rather stout, widely 

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



"See Schioedte and Meinert for charactera of genus, Nat. Tidsskr. (3), XIV, 

 1883-84, pp. 381-383. 



