C HIMzE ROWS. 
33 1 
The fore-limbs were either rudimental or wanting; but a pair of pelvic tins were 
developed. Most or all of the forms may be included in the single family 
CoccosteidcG’, and 
among these the 
genus is dis¬ 
tinguished by the 
absence of any 
pectoral tin, while in 
the allied Brachy- 
° PARTIAL RESTORATION OF THE BERRY-BONE FISH. 
. VUS ^ 11S a PP en ^ a g e (From A. S. Woodward, Cat. Foss. Fishes, Brit. Mus.) 
is represented by a 
hollow spine. In both these the sockets of the eyes form notches on the sides 
of the skull; and the same is the case with the gigantic Dinichthys of the North 
American Devonian. In another group, however, as represented by Homosteus, the 
eye-sockets were completely enclosed in the membrane-bones with which the head 
is covered. 
The Chiivleroids,— Subclass Holocephali. 
Represented by three existing marine genera, of which one has three, the second 
one, and the third two species, and a number of extinct types, the chimseroids form 
a second subclass, agreeing with the lung-fishes in their solid (autostylic) skulls, 
but differing by the total absence of membrane-bones, and their superficial external 
resemblance to sharks. The skeleton is cartilaginous, with the notochord either 
persistent, or constricted and surrounded by cartilaginous rings, which are some¬ 
times partly calcified ; and in the adult the skin is frequently quite naked, although 
.in the young it may bear on the back a series of structures similar in composition 
to teeth, some extinct forms having plates of the same nature. In the existing 
members of the group the optic nerves simply cross one another, and the intestine 
has a spiral valve; while further resemblances to the sharks are shown by the 
presence of claspers in the males, and also by the large size and small number of 
the single eggs. The four gill-clefts open externally by a single aperture on each 
side, protected by a fold of skin containing a cartilaginous operculum. The mouth 
i3 situated at the extremity of the muzzle, and the teeth on the palate and lower 
jaw are molar-like, while there is also a small pair of cutting vomerine teeth in the 
front of the upper jaw; the whole dentition thus closely corresponding to that of 
the lung-fishes, although there are two pairs of upper palatal teeth, which present 
certain hardened areas known as tritors. The pectoral fins are shortened, without 
the segmented axis of the lung-fishes ; and the first dorsal fin may have a movable 
spine articulated to the spinous processes of the vertebrae. The sides of the body 
show a lateral line; but there is no air-bladder, and the nostrils do not open 
behind into the cavity of the mouth. It has been suggested that the chimaeroids 
indicate a degenerate group nearly allied to the lung-fishes, which have lost the 
membrane-bones of the latter, and acquired a superficial resemblance to sharks. 
The ugly fish, to which the name chimaera has been applied ( Chimcera 
monstrosa), together with two other existing species, typically represents the 
family Chimceridce, which alone has survived to the present day. The family is 
