The brain of Acipenser. 157 
spinal V tract. KINGSBURY mentions in Amia a spinal V root going 
out near the sensory VII, but he did not trace it to its rami. 
Special cutaneous components. — The presence in fishes 
generally of dorsally situated nerve roots whose fibres are destined 
to the innervation of canal organs has long been known. The group- 
ing of these organs and their nerves with the pit organs, the ves- 
icles of Savi, and the ampullae of LORENZINI with their nerves, in 
the so-called lateral line system is now generally accepted. STAN- 
NIUS described part of this system in connection with the V—VII 
complex and the remainder as the lateral system of the N. vagus. 
The latter part arises by a single root from the so-called lobus 
posterior of the medulla, crosses the N. vagus from which it receives 
a few fine fibres, and is distributed to the canal organs of the lateral 
line, the opercular, supratemporal, and suprascapular regions. It is 
always the coarse fibres which innervate the canals. The fine fibres 
which STANNIUS found in all the rami may be regarded as general 
cutaneous fibres in accordance with a suggestion of STRONG, or as 
fasciculus communis fibres destined to end buds (HERRICK ’99). 
The first portion of the lateral line system STANNIUS rightly 
describes but, owing to differences which apparently exist between 
Acipenser gturio (described by STANNIUS) and the two species of 
Acipenser studied by GoRONOWITSCH and myself, confusion is likely 
to arise. In describing the V—VII complex STANNIUS takes Pleuro- 
nectes as the type of those forms in which the greatest number 
of distinct roots are found, namely five. These five roots are as 
follows: 
1st root: of mixed, sensory and motor fibres, from the side of 
the medulla. 
2nd ‘and 3rd roots: dorsal roots of coarse sensory fibres from 
the “Lobus medullae oblongatae s. Lobus posterior”, from which 
the R. lateralis of the N. vagus arises. 
Ath root: arises caudal to the 2nd and 3rd and dorsal to the 
ist, and is exclusively of fine sensory fibres. 
5th root: small motor root arising immediately in front of VIII. 
Although he classes Acipenser with Pleuronectes as having five roots, 
it is clear from his description that the two fishes differ widely in 
regard to the first three roots. In Acipenser sturio the roots are 
as follows: 
1st root: small, mostly fine-fibred, sensory. 
