134 PECK. [Vot. III. 
through, showing its extraordinary length and size, and the 
large cells interspersed with fibres. These cells are very large, 
sometimes measuring 36, in length, and 24 in breadth. On 
account of the obliquity of the plane of section, both the dorsal 
and ventral roots are shown upon the left side of the figure 
before their union, showing again the great length of the gan- 
glion structure upon the dorsal root of the more anterior caudal 
nerves. 
Owing to the difficulties of distinguishing the nerves that 
might occur in the last two spaces in the dissections, on account 
of the abundance of connective tissue that obscures them, it is 
possible that a great number of specimens devoted entirely to 
sections might show a larger proportion of cases where nerves 
occur in the anterior one of these spaces. But the results are 
the same in any case, namely, that by the lengthening of the 
caudal series of vertebra, the nerve supply from the cord fol- 
lows in the same, if not an increased ratio; and that the series 
of nerves is always continuous, z.é., consecutive. As there are 
different degrees of anchylosis between the last vertebre and 
the coccyx in different specimens of the same flock, so are there 
different degrees of nerve supply from the cord. And especially 
as the last vertebra is most variable, so is the nerve in this space 
preceding it. Indeed, one series of sections was made in which 
there seemed to be only a single nerve leaving the cord in the 
last space but one, its fellow being wanting on the other side; 
and one specimen had the same appearance in dissection. The 
last vertebra is often found with its neural processes as free as 
any of the others, but with its centrum firmly anchylosed with 
the coccyx of which it thus forms a part. Sections also show 
that the filum terminale is a structure of some importance and 
complexity, and runs far into the coccyx, carrying the two in- 
vesting membranes, the dura mater and pia mater, the former 
of which extends to the extreme end of the spinal canal; and 
that the lumen of the cord persists very plainly to the end, 
where it closes ; also that there is no “cauda equina”’ exactly 
comparable with that which is found in mammals, since the 
nerves originate from the cord at considerable intervals from 
each other; and finally, sections give added evidence to the 
ready variability of the central nervous system in correlation 
with other parts. 
