Proterostomia

Proterostomia

[‚präd·ə·rō′stō·mē·ə]
(zoology)
That part of the animal kingdom in which cleavage of the egg is of the determinate type; includes all bilateral phyla except Echinodermata, Chaetognatha, Pogonophora, Hemichordata, and Chordata.
References in periodicals archive ?
The principal difference in cellular mechanisms of heart-muscle growth between Deuterostomia and Proterostomia may be accounted for by different origin and development of cardiogenic mesoderm in these two main phylogenic taxa.