Cleitro

alt=|thumb|534x534px|Cleithrum and Scapula#In other animals|scapula from a [[wrasse. The larger bone is the cleithrum.]] The cleithrum (: cleithra) is a membrane bone which first appears as part of the skeleton in primitive bony fish, where it runs vertically along the scapula. Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key".