PADDLE FISH ; SEOOg BIEL: 765 
us The remarkably developed gill-rakers of this species thus receive their explanation. 
These aré very numerous and fine, arranged in a double row on each gill arch, and are 
twice as long as the filaments of the gill. By their interlacing they form a strainer 
scarcely less effective than the fringes of the baleen plates of the whale, and probably 
allow the passage of the fine silt of the river bed when this is thrown into the water by 
the shovel of the fish, but arrest everything as large as a Cyclops. The fish is said by the 
fishermen to plow up the mud in feeding with its spatula-like snout, and then to swim 
‘slowly backward through the muddy water. Its mouth, it may he noticed, is very large, 
_ even for a fish. f 
“Ti is possible that this wholesale destruction of entomostraca may affect the food 
supply of other and more valuable fishes, especially of the very young of the predaceous 
species, We cannot yet say, however, where the stress of the struggle comes in the life 
_ of any given species, and consequently are unable either to relieve or heighten it at 
| will, or to perceive the full effect of the forces already at work. Fuller knowledgp 
must precede any but the most cautious and conservative recommendations.” 
Synonymy.—T his species was first described by Lacepede, under the 
| generic name of Polyodon, in reference to the very numerous teeth in the 
| jaws and palate, which character was considered to distinguish the genus 
| from its relatives, the Sharks and the Sturgeons. Lacepede’s deserip tion, 
which is a very minute and excellent one, was made up from numerous 
young specimens preserved in the French Museum under the name of 
» “Chien de mer feuille’. The original locality of these specimens was 
| unknown, as Lacepide remarks, “Nous ne pouvons cependant rien con- 
jecturer relativement ases habitudes; sur lesquelies nous navons recu 
aucun renseignement, non plus que sur les mers qu’elle habite; tout ce 
que nous pouvons dire, c’est que, par une suite dela conformation de ce 
» Polyodon, elles doivent, pour ainsi dire tenir le milieu entre-celles des. 
» squales et celles des acipensires.” 
| A few years later, this fish was again described under the name Spatu. 
a laria reticulata Shaw, aud this name has been, of late years, occasionally 
) employed by writers in spite of the unquestionable priority of Polyodon 
| folum, on the ground of the inappropriateness of the latter name, the 
| adult fish being often without teeth. There is, however, no good ground 
for setting aside Polyodon, even if Spatularia seems a more pleasing name. 
| The fish dogs have many teeth, even if they ultimately fall out, and 
Polyodon it must remain. 
P= Still later, old s specimens received the name of Platirostra edentula, they 
| being considered to form a genus distinct from Polyodon, on account of 
q ‘their toothlessness, and of certain alleged differences in form. The 
identity of Platirostra with Polyodon remained undiscovered until com- 
paratively recently. 
Lastly comes the name Planirostra spatula, apparently given with full 
