THE LATERAL LINE SYSTEM IN EXTINCT 
AMPHIBIA. 
Roy L. Moonie. 
The University of Chicago. 
The study of the system of canals and sense organs in the 
lower vertebrates, known as the lateral line system, has inter- 
ested many anatomists. The existence of the lateral line 
system was first observed, of course, in the fishes where it 
is clearly marked, more especially on the body of the fish. 
According to Collinge (1), the lateral line organs were first 
observed on a species of skate by Stenonis in 1664, and in 
1669 on some of the sharks. The term canal was first applied 
to this set of structures under the preconceived idea that there 
was an actual canal under the skin, as indeed there seems to 
be in some cases, and M’Donnell (2) tells us of his attempts 
to inject the system of canals with a syringe. Various means 
were devised for studying the anatomy of this peculiar set 
of structures and many theories were propounded as to its 
possible functions. The general opinion was that the lateral 
line structures were secreting organs and the grooves on the 
crania of fishes and on the skulls of the ancient Amphibia are 
almost universally spoken of as slime canals or mucous canals 
or grooves. 
Through the recent embryological and anatomical studies of 
Allis, Pollard, Platt, Collinge, Cole, Parker, Takahashi, Har- 
rison, and others, the full development and functions of the 
lateral line system have been made out in a few forms. 
It is now generally admitted, especially since the excellent 
experiments of Parker (3) on the function of these organs in 
fishes, that the lateral line system is a set of-sense organs inter- 
mediate in function between the organs of touch and those 
of hearing, but more delicate than either in some respects. 
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