THE 
AMERICAN NATURALIST. 
VoL. xiv. — FEBRUARY, 1880. — No. 2. 
OBSERVATIONS UPON THE HABITS, STRUCTURE 
AND DEVELOPMENT OF AMPHIOXUS LANGE 
OLA TUS, 
BY HENRY J. RICE. 
[Concluded from the Fanuary number.) 
Nervous System—This system consists of a central and a per- 
ipheral portion. The central portion, or chorda spinalis, is a long, 
slender, slightly tapering body, nearly round in section, and ex- — 
tends from the posterior to within a short distance of the anterior 
extremity of the dorsal aspect of the notochord. The anterior end 
is somewhat larger, for a short distance, than the rest of the chor- 
da, and forms a sort of elongated head with a short, pointed, beak- 
like termination, which lies close upon the notochord. Upon the 
left side of this “head,” and near the end or anterior portion, there 
_ isa slight cone-like projection, which is in close proximity to and 
_ points towards the ciliated pit or depression of the left side of the Nee 
body. This projection is considered to represent a single olfac- 
2 tory nerve or lobe, and if the pit is indeed a ‘nasal fosse, then 
_ undoubtedly this protuberance is an olfactory organ. With the ; 
: Present the slightest indication of the divisions or lobes which 
. Tee m the brain of all other vertebrates. 
ee _The posterior extremity of the chorda mie a adá upward 
n bena, at nearly right angles to its former direction, and expands 
just above the end of the notochord, into a small, button-like ter- j 
- mination, which probably through some accident in finishir z ie 
plate, is not shown in the figure of the adult animal, Between the 
two ends and along the center of the chorda there extends a nat 
rom canal , Which i is of considerable size in the head por ic 
= hg S enclosed by the anterior walls, but gr l; 
amn meia the of se itr extremity, v rh 
