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114 MEMOIRS OF THE NATIONAL ACADEMY OF SCIEXOES. 
tered cells and some fibers, the latter layer being quite distinguishable from the cellular layer and 
reaching nearer the eye.* 
If there were a mass of optic nerves enlarging in bulk towards the retina of the eye, it seems 
to me we should, out of several hundred sections, horizontal, transverse, and longitudinal, have 
detected some traces of it, since it is so large in normal Julidse. It would seem that if an 
optic nerve were present that at least one section would have shown the nerve corresponding to 
that represented by Graberf in his section of the head of Julus sabulosus. It is still possible 
that sections of other specimens may reveal a more or less developed optic nerve sending fibers to 
each facet. 
The eyes are represented by the corneal lenses, the ends of which are buried in the thick, 
well-developed retime. Whether any retinal rods and cells, such as those discovered by Gre¬ 
nadier,! exist in the retina I have not attempted to discover. The corneal lens appears to be well 
developed in the case of each facet present. 
PI. XXIV, figs. 12 and 13 represent sections still lower down, passing through the facets, but 
below the optic ganglia. 
In this connection we may draw attention to the normal development of the olfactory ganglion 
and the antennal or olfactory nerve arising from it (PI. XXV, figs. 1 to 3). In Fig. 1 the pro¬ 
cerebral lobes (pro. 1.) and subcesophageal ganglion (sg.) are shown. In Fig. 2 the entire left 
olfactory ganglion is shown originating in lobular masses, and in the section it is of a slightly 
darker shade than the myeloid substance of the procerebrum. The antennal nerve is well devel¬ 
oped. In a nearly horizontal section farther down (Fig. 3) the right olfactory lobe was cut 
through on one side, where it is separated at this point by a stratum of ganglion cells. The 
origin of the antennal nerve (ant. n.) is also well shown. The section also passed through the thick 
commissure connecting the supra- and subcesophageal ganglia, and in the section forming a thick 
ring around the oesophagus. 
The brain of Scoterpes .— It is now interesting to turn to the brain of Scoterpes (from Mammoth 
Cave), which has even no traces of eyes, and study the modification to which the brain is subjected 
as apparently the result of the total atrophy and disappearance of the eyes. The heads of two 
specimens were each cut into fifty transverse sections. No traces of the optic ganglia, optic 
nerves, or any part of the eyes, including the pigment of the retina or the corneal lenses, were 
to be discovered. So far as these sections show, every trace of the organs of vision and the nerves 
and ganglia supplying them are wanting in this genus. On the other hand, it may be remarked 
that, so far as we have been able to see, the structure of the procerebral, olfactory, and commis¬ 
sural lobes remain unaltered. As in all the other blind or eyeless forms examined, the supra- 
oesopliageal nerve-centers are not affected by the loss of eyes. This is as we might expect, for, the 
sense of smell being rendered more acute, the olfactory organs are somewhat hypertrophied to 
compensate for the atrophy of the organs of vision. We should not expect the central portion of 
the brain, that controlling and co-ordinating the movements of the antennae and other parts of 
the body, to be materially modified. Hence, as seen in the sketches we have made of selected 
sections, the brain is as large in the eyeless Scoterpes, the cortical stratum of ganglion cells as 
thick, and the myeloid substance of each ganglion as perfectly developed as in the allied forms 
with completely developed eyes. 
PI. XXY, figs. 4 and 5 represent sections through the brain of one specimen, and Figs. 6 to 10 
thinner sections through the brain of the other specimen. In all the sections the optic ganglia 
were not to be found, and they evidently are atrophied, with no traces of any differentiation from 
the central procerebral lobes, unless the outer rounded portion of the upper or pro cerebral lobes 
be the rudiments of the optic ganglia, which scarcely seems probable. 
# Tlie lithographer has scarcely done justice to the author’s drawings for Plates XXIV and XXV, having shaded 
parts left blank, and not having clearly brought out the eyes. 
t Ueber das unicorneale Tracheaten- und speciell das Arachnoideen- und Myriopoden-Auge. Von V. Graber. 
Archiv fur rnikr. Anat., Bd. XVII, Heft 1, 58, Taf. VI, fig. 20. 
t Grenacher’s Ueber die Augen einiger Myriopoden. Archiv fur mikr. Anat., Bd. XVII, Heft 4, 415, Taf. XXI, 
fig. U. 
