18 
ganglia of the cranial segments) of the Necrophlugeeophus longicornis 
has been discovered by Newport, at the period of its bursting its 
shell, to consist of four double ganglia (Newport in Phil. Trans. 
1843). 
We next consider the reasons for supposing that the organs com¬ 
posing the mouth of the T ertebrat a should he the homologv.es of 
those of locomotion. It must be remarked, that everything now to 
be said assists most strictly in support of the preceding proposition, 
and would have been introduced under that head but for the sake ot 
conveniency in illustrating the vertebrate skeleton. 
1. In the Crustaceans the jaws differ in scarcely any other cha¬ 
racter than size from the true legs used in locomotion. 
2. In the Myriapoda the members of the basilar segments of the 
head are jointed and retain the form of true legs, but are used for 
prehension (Newport in Todd’s Cyclopaedia). 
3. In Insects the tarsal joints of the cranial legs are undeveloped; 
the femur and coxa are small or confluent with the under side ol the 
segment, whilst the tibiae are alone enormously enlarged, and thus 
become elements in the complex mouth of Insects; their muscles, 
however, being attached to the basilar and posterior lateral parts ot 
the head, just as if they still subserved the purposes of locomotion 
(idem). 
4. All the parts of the complex mouth of Insects are thus referable 
to the segments of the head. In the Great W ater Beetle this is 
clearly shown ; the manducatory organs visibly resemble the proper 
organs of locomotion, and are articulated to the distinct segments 
(idem). 
5. We must remark intermediate normal conditions between the 
true locomotive and manducatory form of leg ; as in the genus Onitis, 
where the prothoracic legs are without tarsi, and the tibiae are termi¬ 
nated by sharp hooks; and in the Bubos bison, a species ot a neigh¬ 
bouring genus, wdiere the tibiae strongly approach in form the proper 
mandibles of the head: also, 
6. A monstrous condition in a specimen of Geotrupes stercora- 
rius, where the prothoracic legs were arrested in development and the 
tarsi were absent, so that they very closely resembled the form ot the 
mandibles (idem). 
Section III. 
The spinal cord of the Vertebrata is homologous with the gan¬ 
glionic cord of the Articulata. 
1. The elements of the systems are alike, being in both cases 
cellular nervous matter and commissural fibres. 
2. The experiments and investigations of recent physiologists have 
proved the real independence of the segments of the cord contained 
in each vertebra, insomuch as each performs separately from the 
others its own reflex actions, just as is the case in the ganglionic cord 
of the Articulata ; so that, as far as its reflex actions are concerned, 
the cellular or dynamic element of the spinal cord is not one organ 
or centre, but a series of independent organs or centres, as is seen m 
