Bivium

• (n.) One side of an echinoderm, including a pair of ambulacra, in distinction from the opposite side (trivium), which includes three ambulacra.
Found on http://thinkexist.com/dictionary/meaning/bivium/

Bivium

Biv'i·um noun [ Latin , a place with two ways. See Bivious .] (Zoology) One side of an echinoderm, including a pair of ambulacra, in distinction from the opposite side ( trivium ), which includes three ambulacra.
Found on http://www.encyclo.co.uk/webster/B/59
No exact match found