Blastoidea :: Blastoidea (n. pl.) One of the divisions of Crinoidea found fossil in paleozoic rocks; pentremites. They are so named on account of their budlike form.
Blastomere :: Blastomere (n.) One of the segments first formed by the division of the ovum.
Blastopore :: Blastopore (n.) The pore or opening leading into the cavity of invagination, or archenteron..
Blastosphere :: Blastosphere (n.) The hollow globe or sphere formed by the arrangement of the blastomeres on the periphery of an impregnated ovum.
Blastostyle :: Blastostyle (n.) In certain hydroids, an imperfect zooid, whose special function is to produce medusoid buds. See Hydroidea, and Athecata..