The Collaborative International Dictionary of English v.0.48:

Hypoblast \Hy"po*blast\, n. [Pref. hypo- + -blast.] (Biol.)
   The inner or lower layer of the blastoderm; -- called also
   endoderm, entoderm, and sometimes hypoderm. See Illust.
   of Blastoderm, Delamination, and Ectoderm.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hypoderm \Hyp"o*derm\, n. [Pref. hypo- + -derm.] (Biol.)
   Same as Hypoblast.
   [1913 Webster]