GANOIDS. 
5°8 
The Bow-Fin and its Allies, —Suborder Protospondyli. 
The so-called bow-fin (4mm calva) of the fresh waters of the United States 
is the sole existing representative of a second and larger subordinal group, differ¬ 
ing from the last by the imperfect ossification of the skeleton, the notochord being 
either persistent throughout life, or if more or less completely replaced by vertebrae, 
those in front of the caudal region have their bodies composed of three distinct 
elements (pleurocentra and intercentrum), which remain separate and alternating 
even when fully developed. The lower jaw is complex, and composed of several 
pieces; in the pectoral arch the infraclavicular plate is absent; and the pectoral fin has 
more than three basal elements belonging to the true internal skeleton; while the 
tail is always abbreviated heterocercal. 
the bow-fin (r nat. size). 
Together with three extinct genera, the bow-fin constitutes a 
Existing Family. ^{ m iido 3 ) characterised as follows. The lower jaw has its 
suspending arrangement directed backwards, and the cleft of the mouth is wide; 
the degree of ossification of the vertebrae is variable, although these often form 
complete discs ; the body is elongate or fusiform; the margins of the jaws are 
armed with an outer series of large and conical teeth, internally to which are 
smaller ones ; fulcra to the fins are either wanting or of minute size ; and the 
dorsal fin is of variable, although usually of considerable length. Having the scales 
thin, somewhat rounded, and overlapping, the bow-fin represents a genus in which 
there are no fulcra, and the long dorsal fin occupies three-fourths the length of the 
body, while the anal fin is short, the caudal rounded, and the throat furnished with 
a single gular plate, followed by a number of branchiostegal rays. The single 
existing species of the genus, which attains a length of 2 feet, is confined to the 
fresh waters of the United States, where it is exceedingly abundant in some of the 
