The Collaborative International Dictionary of English v.0.48:

Heterosomati \Het`e*ro*so"ma*ti\, n. pl. [NL., fr. Gr. ? other +
   ?, ?, body.] (Zool.)
   An order of fishes, comprising the flounders, halibut, sole,
   etc., having the body and head asymmetrical, with both eyes
   on one side. Called also Heterosomata, Heterosomi.
   Heterosporic

WordNet (r) 3.0 (2006):

Heterosomata
    n 1: flatfishes: halibut; sole; flounder; plaice; turbot;
         tonguefishes [syn: Heterosomata, order Heterosomata,
         order Pleuronectiformes]