Crucilobiceras is an ammonoid cephalopod genus from the Lower Jurassic belonging to the eoderoceratacean family Eoderoceratidae

Eoderoceratidae

The Eoderoceratidae is the ancestral and most primitive family of the Eoderocerataceae; lower Jurassic ammonite cephalopods, characterized by evolute, commonly serpenticonic, shells that had long body chambers and would have had no stable floating position; and thus resemble contemporary...

. Cruciliboceras has an evolute shell, such that all whorls are well exposed, with persistent radial ribbing and with spines or tubercles on the outer, ventral, rim, and in some, tubercles in the inner, umbilical, rim.

Metaderoceras, named by Leonard Spath

Leonard Frank Spath

Leonard Frank Spath was a British paleomalacologist and an ammonitologist, a specialist of ammonites.He gained a B.Sc in geology at Birkbeck College in 1912 and obtained employment at the British Museum as an assistant curator in the geology department...

 in 1925, is a jr. synonym for Crucilobiceras named by S.S. Buckman in 1920 according to Arkell et al, in the Treatise on Invertebrate Paleontology

Treatise on Invertebrate Paleontology

The Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and...

(1957).