30 The Dissection of the Fish 
lived, and some may be even annual, dying after spawning, per- 
haps at the end of the first season. 
Teeth are wholly absent in several groups of fishes. They 
are, however, usually present on the premaxillary, dentary, and 
pharyngeal bones. In the higher forms, the vomer, palatines, 
and gill-rakers are rarely without teeth, and in many cases the 
pterygoids, sphenoids, and the bones of the tongue are similarly 
armed. 
No salivary glands or palatine velum are developed in fishes. 
The tongue is always bony or gristly and immovable. Some- 
times taste-buds are developed on it, and sometimes these are 
found on the barbels outside the mouth. 
The Alimentary Canal.—The mouth-cavity opens through the 
pharynx between the upper and lower pharyngeal bones into the 
Fic. 19.—Sheepshead (with incisor teeth), Archosargus probatocephalus (Wal- 
baum). Beaufort, N. C. 
cesophagus, whence the food passes into the stomach. The intes- 
tinal tract is in general divided into four portions—cesophagus, 
stomach, small and large intestines. But these divisions of the 
intestines are not always recognizable, and in the very lowest 
forms, as in the lancelet, the stomach is a simple straight tube 
without subdivision. 
In the lampreys there is a distinction only of the cesoph- 
agus with many longitudinal folds and the intestine with but 
