216 JouRNAL oF CoMPARATIVE NEUROLOGY. 
usage of WricuT, these may all be termed neuromasts, a term 
used by him as equivalent to the Mervenhiigel of MERKEL. 
These types of organs are, (1) the canal organs, or sensory 
organs within the true lateral line canals; (2) the small pit 
organs, or similar sensory organs sunken into separate pits 
which have no connection with the lateral line canals; (3) larger 
sensory organs lying in the epidermis and nearly flush with its 
surface. These I have termed large pit organs and their struc- 
ture differs in some respects from that of the other two types 
of organs. 
I. The lateral line canals and their sense organs in Amewurus 
melas. 
Athough the lateralis system as a whole is unusually highly 
developed, the lateral line canals themselves are not so, but 
present a very simple arrangement conforming closely to the 
teleostean type schema. The pores are never dendritic, as in 
Amia, but are simple and for the most part bear the typical 
relations to the sense organs and the cranial bones. In short, 
the specialized features of the lateralis system are found in the 
pit organs, not in the canals or their organs. The canals will 
be described under the head of supra-orbital, infra-orbital, oper- 
culo-mandibular and main canals, the latter being defined as the 
canal running caudad into the trunk from the point of union of 
the supra-orbital and infra-orbital canals. The relations of these 
canals to each other, to their sense organs and their nerves, 
and to such of the cranial bones as contain them are indicated 
on Fig. 1, in which the sense organs of each canal are num- 
bered consecutively from before with Arabic figures and the 
pores with Roman numerals. This figure also shows the posi- 
tions of the large pit organs, but not of the small pit organs. 
a. The supra-orlital canal. The supra-orbital canal lies 
entirely in the nasal and frontal bones. It opens at each end 
upon the surface by means of pores and contains five sense 
organs, all separated by simple dermal tubules and surface 
pores save the last two. The most cephalic terminal pore opens 
just internally to the anterior nasal aperture at the anterior end 
