5° ROY L. MOODIE 
sense organs were undoubtedly located beneath specialized pigmented 
scales on the surface of the animal’s body and to this pigment is due 
the preservation of the lines. 
The fact that the arrangement of the sense organs of Micrer peton 
corresponds so exactly to the condition found in Necturus is of consider- 
able interest. Necturus alone among the modern tailed Amphibia 
has the arrangement above described for the lateral line system in 
Micrerpeton. All other forms of the Caudata as also the larval forms 
of the Salientia have an arrangement of the lateral line system which 
is perfectly distinct from that found in Necturus, although the 
basal arrangement is the same in nearly all forms. In Ambystoma, 
for instance, the median lateral line is not present on the tail and the 
dorsal line is but incompletely developed. The close similarity of the 
arrangement of the systems of sense organs in the two forms, Mzcrer- 
peton and Necturus, may be of genetic significance with regard to the 
latter form. The lateral line sense organs are of a very fundamental 
significance and it is not at all improbable that the same arrangement 
of the lines has existed from the Carboniferous times down to the 
present. We know that such has been the case in a great many of the 
fishes. ‘The ancestors of the modern Caudata must have originated 
somewhere in the Carboniferous or earlier periods and it is the 
opinion of the writer that the Branchiosauria represent the direct 
ancestral forms for this group of the modern Amphibia. ‘This sug- 
gestion is by no means new, since Baur and others have held the same 
view. The writer hopes to present a fuller discussion of this topic at 
some future time. 
-The relations of the form Mucrerpeton caudatum are readily 
determined. The number of the presacral vertebrae, the form and 
position of the ribs, the shape of the skull, the arrangement of the 
cranial elements, the structure of the pectoral girdle, and the char- 
acter of the ventral armature all clearly bespeak a close relationship 
with Branchiosaurus, Melanerpeton, and Pelosaurus from the Lower 
Permian and Upper Carboniferous of Europe. The distinction of the 
genus Micrerpeton from the other known branchiosaurian genera is 
found in the apparent absence of sclerotic plates, the shape of the 
skull, the arrangement of the cranial elements and the form of the 
ilium. 
