96 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
dissections indicated a connection with the median -sympathetie 
trunk, the study of sections shows this to be only a connective-tissue 
union, the sympathetic bundle passing directly across without any 
break in its sheath that would indicate the passage of nerve fibers. — 
V. GENERAL CONSIDERATIONS ON NERVE XII AND 
THE SPINAL NERVES. 
From a comparative standpoint the hypoglossal nerve in Anolis 
presents two questions for consideration: First, as to the number of 
spinal nerves that enter into its formation and their position in the 
series of spino-occipital nerves, and, secondly, as to the differentiation 
of its component neurons from the typical somatic-motor type from 
which they come. The first question appears to be answered in part 
by the obvious facts presented by Anolis itself, through the persistence 
of three distinct occipital foramina, indicating three separate seg: 
mental nerves. Only rarely have three cranial roots for XII beer 
described in the adult saurian. Among all those described by Fische 
(52, p. 66), three roots are mentioned for only Platydactylus; bu 
in Anolis not only are there three roots, but they emerge throug! 
separate foramina. In two species he finds only one root, and ii 
seven he finds two. In all cases XII either unites with the first spine 
or receives branches from it. Fischer states that, as a rule, the firs 
two spinal nerves are without dorsal roots and ganglia, although some 
times there occurs a weak dorsal root on the second spinal nerve. A 
in Anolis, the third is a nerve well developed in both its motor an 
sensory components. The relation of XII to the spinal nerves vari 
according to the strength and number of its roots. This fact poin 
to the correctness of Fischer’s view that the cranial part of XII do 
not represent the same number of spinal nerves in all lizards. Fi 
bringer (’97, p. 501) arrives at the constant number of three roots! 
all sauropsida, although the first and second emerge through a comm 
foramen in most reptiles. Reference to Fiirbringer’s table (p. 54 
shows his conclusion regarding the homologies of these nerves. ! 
designates them, the first three, as occipito-spinal nerves, their positi_ 
being fixed through discovery in the embryo of the older occipi 
nerves (anterior to these), which havea transitory existence. Tht 
are two features in the twelfth nerve of Anolis which seem to shi 
that it is less completely incorporated into the head than in other r 
