flatworm. see Platyhelminthes Platyhelminthes, phylum containing about 20,000 species of soft-bodied, bilaterally symmetrical, invertebrate animals, commonly called flatworms.There are four classes: the free-living, primarily aquatic class, Turbellaria, and Trematoda, Cestoda, and Monogenea, which are.....ee Platyhelminthes Platyhelminthes, phylum containing about 20,000 species of soft-bodied, bilaterally symmetrical, invertebrate animals, commonly called flatworms.
Freebase(0.00 / 0 votes)Rate this definition: Pro rata. Pro rata is an adverb or adjective, meaning in proportion. The term is used in many legal and economic contexts. It is sometimes spelled pro-rata, but this is technically a misspelling of the Latin phrase. In North American English this term has been vernacularized to prorated.
In 1929, the US Treasury shifted from the fixed-price subscription system to a system of auctioning where 'Treasury Bills' would be sold to the highest bidder. Securities were then issued on a pro rata system where securities would be allocated to the highest bidder until their demand was full.