In all these families spines and glandular papillae may be super-added.
Having no spines to their fins, the Gadids used, in Cuvierian days, to be associated with the herrings, Salmonids, pike, &c., in the artificially-conceived order of Malacopterygians, or soft-finned bony fishes.
Males of the little water-bugs of the genus Corixa make a shrill chirping note by drawing a row of teeth on the flattened fore-foot across a group of spines on the haunch of the opposite leg.
The spines are mixed with long soft hairs.
Among the ammonites the loss of power to coil the shell is one feature of racial old age, and in others old age is accompanied by closer coiling and loss of surface ornamentation, such as spines, ribs, spirals; while in other forms an arresting of variability precedes extinction.
