Dicyemidae

Dicyemidae, a family of Mesozoa, the supposed group of animals intervening- between the Protozoa (or unicellular) and Metazoa (or multicellular animals). Each Dicyemid is composed of two parts, a head (or calotte) and a body. There is no differentiation of the cells into two layers separated by an intermediate mesoglcea or mesoderm. There are, however, some germ cells in the large original interior or "endoderm" cell; these may represent the intervening layers. All the supposed Mesozoa are parasitic, and it is therefore most likely that they are degenerate Metazoa; the question is, however, a difficult one, and is at present unsettled. The Dicyemidee are all parasitic on Cuttlefish.