1. (furca) The springing organ of Collembola, which arises from the fourth or fifth abdominal segment. The furcula comprises a single basal portion, the manubrium, which gives rise to two dens, which terminate in lamellate mucrones (see MUCRO). It is bent forwards and beneath the body to engage on a ventral tube or retinaculum, which acts as a catch. When the furcula is released, the energy stored propels the animal upwards and forwards, sometimes in a tumbling fashion.
2. The wishbone of birds and some Therapoda, supposedly formed by the fusion of clavicles and interclavicle.
"furcula." A Dictionary of Zoology. . Encyclopedia.com. (October 21, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/furcula
"furcula." A Dictionary of Zoology. . Retrieved October 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/furcula