ISOPODA 



375 



^GA Leach. Body elliptical in outline ; basal segments of first anten- 

 nae expanded and lying entirely in front of the head : 14 American species. 



A. psora (L.). Salve bug (Fig. 595). Length 16 mm.; breadth 10 

 mm.: parasitic on the skate, cod, halibut, and other fishes; 

 used as a salve by fishermen; Long Island Sound to 

 Greenland; Gulf of Mexico; Europe. 



Family 5. CYMOTHOIDAE. 



Head triangular, with large eyes, and extending over 

 the base of the short antennae; all 7 pairs of legs pre- 

 hensile, terminating in hooks: parasitic on fishes; over 

 100 species, 27 American. 



LivoNECA Leach. Body elliptical, more or less 

 asymmetrical; first pair of antennae widely separated at the base: 5 

 American species. 



L. ovalis (Say). Length 21 mm.; width 13 mm.: 

 parasitic on the gills and in the mouth of the bluefish and 

 occasionally of other fishes along the Atlantic coast south 

 of Cape Cod, and in the Gulf of Mexico. 



Fig. 595 

 ^ga psora 

 (llarger). 



Fig. 596 

 Limnoria 

 lignorum 

 (Harger). 



Family 6. LIMNORIIDAE. 



Body flattened and with parallel sides; can roll itself 

 into a ball; antennae short; eyes lateral; uropods lateral; 

 legs ambulatory: 1 genus. 



Limnoria Leach. With characters of family : 1 species. 

 L. lignorum (Rathke). Gribble (Fig. 596). Length 3 mm.; width 

 1.5 mm. : Florida to Labrador ; Europe ; Pacific coast ; makes burrows 

 about 12 mm. deep in submerged timbers, causing 

 great damage to docks, etc.; very common. 



Family. 7. SPH^ROMIDAE. 



Body short, oval, and convex, and in many species 

 can be rolled into a ball; but 1 abdominal segment 

 besides the large telson; inner branch of uropod 

 immovable: 30 American species. 



SPH2ER0MA Latreille. Uropods large, lateral, the 

 2 branches being of equal length, the outer margin of 

 the exopodite being denticulate; legs ambulatory: 3 

 American species. 



S. quadridentatum Say (Fig. 597). Body can be rolled into a ball; 

 length 8 mm. ; width 4 mm. ; color dark and variable : Florida to Cape 

 Cod; under stones between tide lines. 



Fig. 597 



^phwroma 



quadridentatum 



(llarger). 



