208 RALPH EDWARD SHELDON 
end in the lobus olfactorius posterior, pars lateralis, of the oppo- 
site side. The remaining two bundles originate from the formatio 
bulbaris; the more medial forms the commissura olfactoria inter- 
bulbaris, while the more lateral ends in the lobus olfactorius 
posterior, pars medialis, in which are confused the precommissural 
body and the epistriatum of Edinger. Kappers (’06) observes two 
different conditions in the teleosts examined by him. The lateral 
tract, or radix olfactoria lateralis, always ends inthe area olfactoria 
posterior lateralis (area olfactoria of Edinger) ; in Gadus, Thynnus 
and Lophius it ends on the same side, however, while in Salmo 
it decussates in the apterior commissure to end in the opposite 
side. Kappers also finds that the medial tract is composed of 
two parts, a medial tractus olfacto-lobaris medialis and a lateral 
radix olfactoria medialis propria. He finds that both sets of 
fibers decussate and that most of them end in the area olfactoria 
posterior medialis, here termed epistriatum, although a few in 
Salmo may end in the lateral area. 
In none of the previous work on these tracts in fishes have all 
of the connections been brought out. This is undoubtedly due, 
in part, to the lack of a detailed study of the olfactory bulb and 
in part to a failure to learn the direction of the different compo- 
nents by the use of the Golgi method. — 
The olfactory crura in the carp, as previously noted, are very 
long and in transections at different levels, the apparent number 
of tracts varies considerably. In some sections only one or two 
bundles will appear, while in others ten or twelve may be seen. 
In order to determine the number and relations of these bundles, 
plots were made of several complete series of serial sections of the 
crura, showing the number of bundles appearing in each section 
and their relation to one another. Micrometer measurements 
were used to determine the relations in all doubtful cases; that is 
to say, whenever in one section two bundles were found, and 
in the next section three, measurements were taken if there was 
any doubt as to which of the two gave rise to the third. In this 
way, it is possible to determine the number of important fiber 
bundles in the crura and by tracing them to their origin and ter- 
mination, learn their relation to the centers of the bulbs and basal 
