522 WALTER EDWARD COLLINGE. 
beim Stor drei vorfinden, ein paariges, oben genanntes, und ein 
unpaares medianes (Supraoccipitale). 
“Der suborbitale Zweig verlasst den Haupstamm in der 
Mitte des Squamosums, tritt dann in das (dermo-) Post- 
frontale und liuft weiter nach vorn durch die beiden Infra- 
orbitalia.”’ 
In a foot-note he says :— 
“Die Lage der Schleimcanale ist von hohen Interesse bei 
der Bestimmung der Deckknochen des Schadels, weil sie in 
Hinsicht auf diese ziemlich constante Beziehungen zeigt.” 
Commencing some 13} mm. from the tip of the dorsal caudal 
fin the lateral canal traverses a number of isolated scutes, an- 
teriorly becoming more dorsal it enters the skull by traversing 
the dermal ossifications which connect the pectoral arch. 
Short branches are here given off which ramify the bone. In 
the post-temporal an occipital commissure passes off from the 
main canal, which is continued forwards through the epiotic 
and squamosal. In the squamosal the canal divides into a 
supra- and sub-orbital branch, the former continuing through 
the frontal, and passes outwards and downwards behind and 
posterior to the anterior nasal opening and then along the 
rostrum, becoming connected with its fellow half of the oppo- 
site side, and also ventrally with the sub-orbital branch. This 
latter branch passes from the division of the main canal in the 
squamosal into the pre-frontal, and then through a circum- 
orbital series which surround the posterior and ventral borders 
of the orbit, some of which are not visible externally. There 
are four bones in this series. The canal issues from the most 
anterior as a dermal canal, and passes into another series of 
canal bones, which are not unlike in appearance a series of 
miniature drain-pipes ; these conduct the canal to the tip of the 
rostrum, where it now passes into a tooth-shaped bone, in 
which it branches in various directions, the main branch join- 
ing the supra-orbital branch above. 
1. The Lateral Canal.—In Acipenser the lateral canal 
commences about 134 mm. from the tip of the dorsal caudal 
fin, in a series of canal bones. Previous to the commencement 
